HVAC Systems - Automatic Buick LeSabre VIII

SPECIFICATIONS

SPECIFICATIONS

DESCRIPTION & OPERATION

The Air Delivery and air temperature controls description and operation is divided into 9 areas

1. A/C Cycle
2. Air Distribution
3. Air Speed
4. Automatic Operation
5. Engine Coolant
6. Heating and A/C Operation
7. HVAC Control Components
8. Recirculation Operation
9. Steering Wheel Controls

A/C CYCLE

Refrigerant is the key element in an air conditioning system. R-134a is presently the only EPA approved refrigerant for automotive use. R-134a is an very low temperature gas that can transfer the undesirable heat and moisture from the passenger compartment to the outside air.

The A/C compressor is belt driven and operates when the magnetic clutch is engaged. The compressor builds pressure on the vapor refrigerant. Compressing the refrigerant also adds heat to the refrigerant. The refrigerant is discharged from the compressor, through the discharge hose, and forced to flow to the condenser and then through the balance of the A/C system. The A/C system is mechanically protected with the use of a high pressure relief valve. If the high pressure switch were to fail or if the refrigerant system becomes restricted and refrigerant pressure continued to rise, the high pressure relief will pop open and release refrigerant from the system.

Compressed refrigerant enters the condenser in a high temperature, high pressure vapor state. As the refrigerant flows through the condenser, the heat of the refrigerant is transferred to the ambient air passing through the condenser. Cooling the refrigerant causes the refrigerant to condense and change from a vapor to a liquid state.

The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum tubing and aluminum cooling fins, which allows rapid heat transfer for the refrigerant. The semi-cooled liquid refrigerant exits the condenser and flows through the liquid line, to the orifice tube.

The orifice tube is located in the liquid line between the condenser and the evaporator. The orifice tube is the dividing point for the high and the low pressure sides of the A/C system. As the refrigerant passes through the orifice tube, the pressure on the refrigerant is lowered. Due to the pressure differential on the liquid refrigerant, the refrigerant will begin to vaporize at the orifice tube. The orifice tube also meters the amount of liquid refrigerant that can flow into the evaporator.

Refrigerant exiting the orifice tube flows into the evaporator core in a low pressure, liquid state. Ambient air is drawn through the HVAC module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant boil inside of the evaporator core. The boiling refrigerant absorbs the moisture and heat from the ambient air. The refrigerant exits the evaporator through the suction line and back to the compressor, in a vapor state, and completing the A/C cycle of heat removal. At the compressor, the refrigerant is compressed again and the cycle of heat removal is repeated.

The conditioned air is distributed through the HVAC module for passenger comfort. The heat and moisture removed from the passenger compartment will also change form, or condense, and is discharged from the HVAC module as water.

AIR DISTRIBUTION

The HVAC control module controls the mode actuator in order to distribute airflow to a desired outlet. The mode switch provides the vehicle operator with the ability to override the automatic setting. When the mode door is moved to the defrost position, the A/C compressor clutch engages and the recirculation actuator will be moved to the outside air position. Regardless of the mode setting, a small amount of air will be diverted to the defrost ducts to reduce windshield fogging. When VENT is pressed, the following will occur

1. The mode actuator will be moved to the PANEL position.
2. The recirculation actuator will be placed in the OUTSIDE air position.
3. The A/C compressor will be commanded off.

After a malfunction occurs to the mode actuator it is driven to the DEFROST position On start-up, the HVAC control module will place the mode door in the last selected position.

AIR SPEED

The blower motor forces air to circulate within the vehicles interior. The vehicle operator determines the blower motors speed by placing the blower motor switch in a desired speed position or by selecting automatic operation. The blower motor will only operate if the blower motor switch is in any position other than OFF, and the ignition switch is in the RUN position. In manual operation, once a blower speed is selected, the blower speed remains constant until a new speed is selected. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature.

As the requested blower speed increases, the following conditions occur

1. The HVAC control module increases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, decrease.

As the requested blower speed decreases, the following conditions occur

1. The HVAC control module decreases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, increase.

Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned off. This reduces the amount of microbial growth that can create undesirable odors. The vehicle Does Not come equipped with the afterblow feature turned on. If the afterblow feature is required due to an odor concern, it must be turned on by the scan tool.

The following conditions must be met for afterblow to operate

1. The engine has been turned off for more than 45 minutes.
2. The ambient air temperature is more than 70°F (21°C).
3. The A/C compressor operated for more than 3 minutes.
4. The system voltage is at least 12 volts.

Once the above conditions have been met, the blower will run for 4 minutes.

Purge Operation

If the ambient air temperature is less than 35°F (2°C) and the coolant temperature is less than 50°F (10°C), then a 75-second purge will occur. The purge will begin as soon as the coolant temperature reaches 4°F (4°C). The mode door will move to the defrost position and the blower motor will be near half speed.

AUTOMATIC OPERATION

In automatic operation, the HVAC control module will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation. To place the HVAC system in AUTOMATIC mode, the following is required

1. The blower motor switch must be in the AUTO position.
2. The air temperature switch must be in any other position other than 66 or 88 degrees.
3. The mode switch must be in the AUTO position.

Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically be adjusted to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature

1. Monitor the inside air temperature sensor, ambient air temperature sensor, upper air temperature sensor if cool air is required, lower air temperature sensor if warm air is required and sunload sensor.
2. Regulate blower motor speed.
3. Position the air temperature actuator.
4. Position the mode actuator.
5. Position the recirculation actuator.
6. Request A/C operation.

ENGINE COOLANT

Engine coolant is the key element of the heating system. The thermostat controls engine operating coolant temperature. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation. Coolant enters the heater core through the inlet heater hose, in a pressurized state.

The heater core is located inside the HVAC module. The heat of the coolant flowing through the heater core is absorbed by the ambient air drawn through the HVAC module. Heated air is distributed to the passenger compartment, through the HVAC module, for passenger comfort.

The amount of heat delivered to the passenger compartment is controlled by opening or closing the HVAC module air temperature door. The coolant exits the heater core through the return heater hose and recirculated back through the engine cooling system.

HEATING & A/C OPERATION

The purpose of the heating and A/C system is to provide heated and cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. The vehicle operator can determine the passenger compartment temperature by adjusting the air temperature switch. Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve the desired temperature

1. Recirculation actuator setting.
2. Difference between inside and desired temperature.
3. Difference between ambient and desired temperature.
4. Blower motor speed setting.
5. Mode setting.

The IPM makes the following actions when an air temperature setting is selected

1. Warmest Position - The air temperature door diverts maximum air through the heater core.
2. Coldest Position - The air temperature door directs maximum air to bypass the heater core. The blower motor, recirculation actuator, and mode actuator are set to the following positions: Mode actuator - Panel. Blower Motor - High speed. Recirculation actuator - Recirculation.
3. Between The Warmest And Coldest Positions - The following sensor inputs are monitored to determine the air temperature door position that diverts the appropriate amount of air past the heater core in order to achieve the desired temperature: Sunload. Duct temperatures. Ambient temperature. Inside temperature.

The A/C system can be engaged by either pressing the A/C switch or during AUTOMATIC operation. The IPM receives an input from the HVAC control module. In order for the Powertrain Control Module (PCM) to internally ground the A/C compressor clutch relay control circuit, the Dash Integration Module (DIM) and the PCM must communicate to each other over the Class 2 serial data circuits. The PCM monitors the A/C refrigerant line pressure and engine coolant temperature. The DIM monitors the A/C refrigerant line pressure, engine coolant temperature, battery voltage and A/C request from the Instrument Panel Integration Module (IPM).

The DIM will request A/C operation from the PCM if these parameters are within normal operating limits and the ambient temperature is more than 37°F (3°C). If the A/C compressor is turned off due to low ambient temperatures, the A/C compressor will not be turned back on until the ambient temperature reaches 42°F (6°C). Once engaged, the compressor clutch will be disengaged for the following conditions

1. Throttle position is 100 percent.
2. A/C Pressure is more than 430 psi (2968 kPa).
3. A/C Pressure is less than 35 psi (255 kPa).
4. Engine Coolant Temperature (ECT) is more than 259°F (121°C).
5. Engine speed is more than 5000 RPM.
6. Transmission shift.
7. PCM detects excessive torque load.
8. PCM detects insufficient idle quality.
9. PCM detects a hard launch condition.

When the compressor clutch disengages, the compressor clutch diode protects the electrical system from a voltage spike.

A/C Refrigerant Pressure Sensor

The A/C refrigerant pressure sensor is a 3 wire piezoelectric pressure transducer. A 5 volt reference, low reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between zero-5 volts. When the A/C refrigerant pressure is low, the signal value is near zero volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts.

The A/C refrigerant pressure sensor protects the A/C system from operating when an excessively high or low pressure condition exists. The PCM disables the compressor clutch under the following conditions

1. A/C pressure is more than 430 psi (2968 kPa).
2. A/C pressure is less than 35 psi (255 kPa).

Air Temperature Actuator

The actuator is a 5 wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference, control, 5 volt reference and position signal circuits enable the actuator to operate. The control circuit uses either a zero, 2.5 or 5 volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A zero or 5 volt control signal commands the actuator movement in opposite directions. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between zero-5 volts.

The Instrument Panel Integration Module (IPM) uses a range of zero-255 counts to index the actuator position. The door position signal voltage is converted to a zero-255 count range. When the module sets a commanded, or targeted, value, the control signal is changed to either zero or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.

Air Temperature Sensors

The air temperature sensor is a 2 wire negative temperature co-efficient thermistor. The vehicle uses ambient, inside and duct air temperature sensor.

A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor operates within a temperature range of -40°F (-40°C) to 300°F (150°C). The sensor signal decreases as the resistance decreases. The sensor signal varies between zero-5 volts. The IPM converts the signal to a range between zero-255 counts.

The Instrument Panel Integration Module (IPM) uses the sensor signals to determine the air temperature door position. Left and right air temperature sensor inputs in a dual zone HVAC system are used to adjust the corresponding left and right air temperature door. In HVAC systems with upper and lower duct temperature sensors, the IPM uses the Upper sensor inputs with the PANEL and BI-LEVEL mode positions and the Lower sensor inputs with the DEFROST, FLOOR and DEFOG mode positions.

If the IPM detects a malfunctioning sensor, then the control module software will use a defaulted air temperature value. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.

The scan tool has the ability to update the displayed ambient air temperature. The ambient air temperature value is displayed or updated under the following conditions

1. Displays real-time temperature: Engine coolant temperature is less than 18°F (10°C) above the ambient air temperature reading. Engine has not been started in 2 hours.
2. Displays last stored temperature when engine coolant temperature is more than 10°C (18°F) above the sensor reading.
3. Temperature is updated every second: Vehicle speed is more than 10 MPH (16 km/h). 300 second time delay to allow ambient air to cool the sensor. Time delay begins when vehicle speed reaches or maintains at least 10 MPH (16 km/h).

Blower Motor Control Processor

The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a Pulse Width Modulated (PWM) signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

Dual Zone Operation

The right air temperature allows the passenger to offset air discharge temperatures on the right side of the vehicle by 5°F (3°C). To activate the dual zone, the passenger rotates the switch to the desired offset. The switch assembly has LEDs that will illuminate in order to inform the passenger of the temperature offset. The temperature offset is allowed as long as the drivers set temperature is not in the maximum hot or cold settings. The display will not show the passenger temperature selection.

Once the temperature offset request is made to the Front Passenger Door Module (FPDM), the signal is sent to the Driver Door Module (DDM). The DDM is connected to the FPDM through the power door serial data circuit. The DDM will make a request to the IPM through the Class 2 serial data circuit. The Instrument Panel Integration Module (IPM) will position the right air temperature actuator, located on the right side of the HVAC module to a position to divert sufficient air past the heater core to achieve the desired passenger temperature.

HVAC Control Module

The HVAC control module is a device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The control module sends switch input data to the Instrument Panel Integration Module (IPM), and receives display data from the IPM through signal and clock circuits. The ignition 3 voltage circuit provides a device on signal. The control module does not retain any HVAC DTCs or settings.

Instrument Panel Integration Module

A function of the Instrument Panel Integration Module (IPM) operation is to process HVAC system inputs and outputs. Also, the IPM acts as the HVAC control modules class 2 interface. The battery positive voltage circuit provides power that the IPM uses for Keep Alive Memory (KAM). If the battery positive voltage circuit loses power, then all HVAC DTCs and settings will be erased from KAM. The ignition 3 voltage circuit provides a device on signal.

Mode/Recirculation Actuator

The mode/recirculation actuator is a 5 wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference, control, 5 volt reference and position signal circuits enable the actuator to operate. The control circuit uses either a zero, 2.5 or 5 volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A zero or 5 volt control signal commands the actuator movement in opposite directions. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between zero-5 volts.

The HVAC control module uses a range of zero-255 counts to index the actuator position. The door position signal voltage is converted to a zero-255 count range. When the module sets a commanded, or targeted, value, the control signal is changed to either zero or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates, the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.

Sunload Sensor

The sunload sensor is a 2 wire photo diode. The vehicle uses left and right sunload sensors. The 2 sensors are integrated into the sunload sensor assembly. Low reference and signal circuits enable the sensor to operate. As the light shining upon the sensor gets brighter, the sensor conductance increases. The sensor signal decreases as the conductance increases. The sensor operates within an intensity range between completely dark and bright. The sensor signal varies between zero-5 volts. The IPM converts the signal to a range between zero-255 counts.

The sunload sensor provides the IPM a measurement of the amount of light shining on the vehicle. Bright, or high intensity, light causes the vehicles inside temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

If the IPM detects a malfunctioning sensor, then the IPM software will use a defaulted sunload value. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is fixed.

RECIRCULATION OPERATION

The HVAC control module controls the air intake through the recirculation actuator. Recirculation is not available when the mode is in DEFROST. When the mode is in DEFOG, recirculation will only be available for ten minutes. The operator must activate the blower for Recirculation operation. The A/C high-pressure recirculation switch can cause the HVAC system to recirculate air. If the recirculation switch is pressed into the ON position when the mode switch is in an unavailable mode position, then the recirculation switch LED will flash 3 times. When the high side pressure reaches 320-380 psi (2206-2620 kPa), the PCM will place the HVAC system in recirculation mode. The high side pressure is lowered when the inside air cools the refrigerant within the A/C evaporator. When the high-side pressure reaches 210-270 psi (1447-1861 kPa), the PCM will place the HVAC system out of recirculation mode.

STEERING WHEEL CONTROLS

An additional temperature switch is mounted on the steering wheel in order to allow the driver to adjust the HVAC temperature. If the driver adjusts the temperature using the steering wheel temperature control switch, then voltage is sent through a series of resistors. That varied voltage is sent back through the inflatable restraint steering wheel module coil to the DIM through the steering wheel controls signal circuit. Once the DIM receives the varied voltage signal, the information is sent out over the Class 2 serial data circuit to the IPM, where the air temperature actuator is adjusted.

COMPONENT LOCATIONS

COMPONENT LOCATIONS

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Calibration With A Scan Tool

1. Install a scan tool.
2. Turn ignition on.
3. With a scan tool, select INSTRUMENT PANEL MODULE.
4. Select SPECIAL FUNCTIONS.
5. Select MISCELLANEOUS TEST.
6. Select RECALIBRATE ALL MOTORS.
7. Select ON, wait 30 seconds.
8. All counts will display zero and slowly the scan tool will begin to show counts.

Calibration without a Scan Tool

Note. The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds.

1. Turn ignition off.
2. Remove the battery positive voltage circuit fuse of the Instrument Panel Control Module.
3. Wait 60 seconds.
4. Install the fuse.

AFTERBLOW ENABLE

Install scan tool. Turn ignition on. Select INSTRUMENT PANEL MODULE. Select SPECIAL FUNCTIONS. Select SET OPTIONS. Select AFTERBLOW. Select YES to enable afterblow.

TROUBLE SHOOTING

Note. For general A/C-Heater trouble shooting see TROUBLE SHOOTING in LESABRE article in MANUAL HVAC SYSTEMS.

A/C PERFORMANCE TEST

Note. Tools Required: ACR 2000 Air Conditioning Service Center (J-43600).

This test measures the operating efficiency of the A/C system under the following conditions

1. The current ambient air temperature.
2. The current relative humidity.
3. The high-side pressure of the A/C system.
4. The low-side pressure of the A/C system.
5. The temperature of the air being discharged into the passenger compartment.

Note. The ambient air temperature must be more than 60°F (16°C). Do not induce additional air flow across the front of the vehicle during the test. If you were sent here from a DTC diagnostic table, clear the DTC upon completion of this test.

1. Park the vehicle inside or in the shade. Open the windows in order to ventilate the interior of the vehicle. If the A/C system was operating, allow the A/C system to equalize for about 2 minutes. Turn the ignition off. Install the ACR 000 Air Conditioning Service Center. Record the ambient air temperature displayed on the ACR 2000 Air Conditioning Service Center. Record the low and high-side static pressure readings. Are both the low-side and high-side pressures within the specified value? More than 60°F (16°C) - 50 psi (345 kPa). More than 75°F (24°C) - 70 psi (483 kPa). More than 90°F (33°C) - 100 psi (690 kPa). If so, go to next step. If not, check system for a refrigerant leak. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
2. Close the vehicle doors and windows. Open the driver door window 5-6 in. (12.7-15.2 cm). Select the following HVAC control settings: Turn the A/C on. Select RECIRCULATION mode. Select maximum blower speed. Air directed through the I/P panel outlets. The coldest temperature setting. All A/C outlets open. Install the temperature probes of the ACR 2000 Air Conditioning Service Center in the left and right center A/C air outlets. Apply the parking brake. Place the transaxle in the PARK position. Start the engine. Operate the A/C system for 5 minutes. Inspect a/c components for abnormal frost areas and unusual noises. Print the outlet air temperatures, the low-side pressure and the high-side pressure. Compare the low and high-side pressures and the output temperatures to the table. (Scheme 7) Does all the data recorded fall within the specified ranges of the table? If so, go to step 4. If not, go to next step.
3. If the pressures and temperatures recorded do not fall within the specified ranges: Continue to operate the A/C system for an additional 5 minutes. Reset the ACR 2000 Air Conditioning Service Center and record the pressures and temperatures again. Compare the low and high-side pressures and the output temperature to the table. (Scheme 7) Does all the data recorded fall within the specified ranges of the table? If so, go to step 8. If not, go to next step.
4. Do the high and low-side pressures fall within the specified ranges, but the outlet temperatures do not? If so, go to «A/C PRESSURE ZONE "A" DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-pressure-zone-a-diagnosis) under SYSTEM TESTS. If not, go to next step.
5. Is the low-side pressure greater than the specified range, but the high-side pressure within or less than the specified range? If so, go to «A/C PRESSURE ZONE "B" DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-pressure-zone-b-diagnosis) under SYSTEM TESTS. If not, go to next step.
6. Are the low and high-side pressures both greater than the specified ranges? If so, go to «A/C PRESSURE ZONE "C" DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-pressure-zone-c-diagnosis) under SYSTEM TESTS. If not, go to next step.
7. Is the high-side pressure greater than the specified range, but the low-side pressure is within or less than the specified range? If so, go to «A/C PRESSURE ZONE "D" DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-pressure-zone-d-diagnosis) under SYSTEM TESTS. If not, go to next step.
8. Operate the system in order to verify the test results. Did you find the same results? If so, system okay. If not, go to «TROUBLE SHOOTING»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__trouble-shooting).

Scheme 7

HEATER PERFORMANCE TEST

1. Were you sent here from TOO COLD IN VEHICLE? If so, go to next step. If not, go to «TEST O: TOO COLD IN VEHICLE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-o-too-cold-in-vehicle) under SYMPTOM TESTS.
2. Start the engine. Allow the engine to idle. Does the engine reach a normal operating temperature? If so, go to next step. If not, go to step 9 .
3. Allow to idle. Select the FLOOR mode. Select the minimum blower speed. Select the maximum temperature setting. Feel the temperature of the inlet and outlet hoses at the heater core. Does the inlet hose feel warmer than the outlet hose? If so, go to step 7 . If not, go to next step.
4. Install a thermometer into the I/P center air outlet. Secure a thermometer to the heater core outlet hose. Select the VENT mode. Select the maximum blower speed. Select the maximum temperature setting. Record the temperature at the following locations: The I/P center air outlet. The heater core outlet hose. Compare the recorded temperatures. Are the temperatures similar? If so, go to next step. If not, go to step 6 .
5. Inspect and repair the cowl, the recirculation door and the HVAC module case of the vehicle for cold air leaks. See appropriate «REMOVAL & INSTALLATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__removal-installation) procedure. Perform the necessary repairs. After repairs are complete, go to step 10 .
6. Inspect the temperature door operation. See «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM. Perform any necessary repairs. After repairs are complete, go to step 10 .
7. Turn the engine off. Back-flush the heater core. Start the engine. Select the FLOOR mode. Select the minimum blower speed. Select the maximum temperature setting. Feel the temperature of the inlet and outlet hoses at the heater core. Does the inlet hose feel warmer than the outlet hose? If so, go to next step. If not, go to step 10 .
8. Replace the heater core. See «HEATER CORE (WITHOUT CONSOLE)»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__heater-core-without-console) or «HEATER CORE (WITH CONSOLE)»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__heater-core-with-console) under REMOVAL & INSTALLATION. After repairs are complete, go to step 10 .
9. Repair the low engine temperature concern (possible cooling fan or thermostat malfunction). After repairs are complete, go to next step.
10. Operate the system in order to verify the repair. Does the system operate correctly? If so, system okay. If not, go to step 2 .

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Diagnostic Trouble Codes (DTCs) can only be displayed using a scan tool.

Turn ignition switch to ON position. Connect scan tool to Data Link Connector (DLC). DLC is located under instrument panel, near steering column. Retrieve DTCs following manufacturers instructions. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table. To diagnose a non-DTC related concern, see TROUBLE SHOOTING and SYMPTOM TESTS . Clear DTC after completing repairs. See CLEARING TROUBLE CODES .

DIAGNOSTIC TROUBLE CODE IDENTIFICATION

CLEARING TROUBLE CODES

DTCs can be cleared using scan tool or by ignition cycle default. If no DTCs occur for 50 drive cycles (ignition switch cycled on and off 50 times), existing history DTCs will be cleared from programmer memory.

DIAGNOSTIC SYSTEM CHECK

1. Did you review DESCRIPTION & OPERATION? If so, go to next step. If not, go to «DESCRIPTION & OPERATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__description-operation) .
2. Install a scan tool. Does the scan tool power up? If so, go to next step. If not, go to SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Turn ignition on. Attempt to establish communication with the Driver Door Module, Powertrain Control Module, Instrument Panel Integration Module and Dash Integration Module. Does the scan tool communicate with the control modules? If so, go to next step. If not, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
4. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool. Rotate the ignition switch through all positions while observing the IGNITION SWITCH POWER MODE parameter. Does the ignition switch parameter reading match the ignition switch position for all switch positions? If so, go to next step. If not, go to POWER MODE MISMATCH under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
5. Select the display DTCs function on the scan tool for the Driver Door Module, Powertrain Control Module, Instrument Panel Integration Module and Dash Integration Module. Does the scan tool display any DTCs? If so, go to next step. If not, go to «SYMPTOM TESTS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__symptom-tests) .
6. Does the scan tool display any DTCs which begin with a "U"? If so, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If not, go to next step.
7. Does the scan tool display DTC B10XX, except B1000? If so, see «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table. If not, go to next step.
8. Does the scan tool display DTC B1327? If so, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table. If not, go to next step.
9. Does the scan tool display any DTCs which are not associated with the HVAC system? If so, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/buick/lesabre/viii-2000-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) in SELF-DIAGNOSTICS - 3.8L "C", "H" & "W" BODIES article in ENGINE PERFORMANCE. If not, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table.

DTC B0126: UPPER RIGHT AIR TEMPERATURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

Circuit Description

The Instrument Panel Integration Module (IPM) monitors the right A/C duct air temperature through the upper right air temperature sensor. The upper right air temperature sensor is a variable resistor. The IPM supplies 5 volts to the upper right air temperature sensor signal circuit and provides a low reference circuit. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The IPM requests A/C compressor clutch engagement and controls the right air temperature door position in order to maintain the selected air temperature on the right air temperature switch assembly.

Conditions For Running The DTC

The ignition is on.

Conditions For Setting The DTC

The IPM detects the upper right air temperature sensor signal circuit is less than 0.09 volt or greater than 4.90 volts.

Action Taken When The DTC Sets

1. When the ambient air temperature is at or below 59°F (15°C), a default value of 4.80 volts will be substituted for the upper right air temperature sensor data by the IPM. The RIGHT A/C DUCT TEMP displayed on the scan tool is the default value. The RIGHT A/C DUCT TEMP displayed on the scan tool in the Open/Short Data list is the actual value.
2. When the ambient air temperature is at or above 60°F (16°C), a default value of 0.19 volt will be substituted for the upper right air temperature sensor data by the IPM. The RIGHT A/C DUCT TEMP displayed on the scan tool is the default value. The RIGHT A/C DUCT TEMP displayed on the scan tool in the Open/Short Data list is the actual value.

Conditions For Clearing The DTC

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

Diagnostic Aids

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

Diagnostic Procedures

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe RIGHT A/C DUCT TEMP parameter in Instrument Panel Module (IPM) open/short data list. If scan tool indicates RIGHT A/C DUCT TEMP parameter is 0.09-4.90 volts, problem is intermittent. Check wiring and connections. If scan tool indicates RIGHT A/C DUCT TEMP parameter is not 0.09-4.90 volts, go to next step.
3. Turn ignition off. Disconnect upper right air temperature sensor. Turn ignition on. Using scan tool, observe RIGHT A/C DUCT TEMP parameter. If scan tool indicates RIGHT A/C DUCT TEMP parameter is greater than 4.90 volts, go to next step. If scan tool indicates RIGHT A/C DUCT TEMP parameter is less than 4.90 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between upper right air temperature sensor connector terminals "A" (Tan wire) and "B" (Yellow wire). Turn ignition on. Using scan tool, observe RIGHT A/C DUCT TEMP parameter. If scan tool indicates RIGHT A/C DUCT TEMP parameter is less than .09 volt are present, go to step 8 . If scan tool indicates RIGHT A/C DUCT TEMP parameter is greater than .09 volt are present, go to step 6 .
5. Check Tan wire between upper right air temperature sensor connector terminal "A" and IPM connector C2, terminal B7 for a short to ground. Repair Tan wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check Tan wire between upper right air temperature sensor connector terminal "A" and IPM connector C2, terminal B7 for a short to voltage, high resistance or open. Repair Tan wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check Yellow wire between upper right air temperature sensor connector terminal "B" and IPM connector C2, terminal B8 for high resistance. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check upper right air temperature sensor harness connector for poor connections. If problem was found and corrected, go to step 12 . If connections are okay, go to step 10 .
9. Check IPM harness connector for poor connections. If problem was found and corrected, go to step 12 . If connections are okay, go to step 11 .
10. Replace upper right air temperature sensor located behind glove box. Twist sensor 1/4 turn to remove. After repairs are complete, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in BODY CONTROL MODULES article. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B0126 does not reset, system is okay. If DTC B0126 resets, go to step 2 .

DTC B0131: LOWER RIGHT AIR TEMPERATURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) monitors the right heater duct air temperature through the lower right air temperature sensor. The lower right air temperature sensor is a variable resistor. The IPM supplies 5 volts to the lower right air temperature sensor signal circuit and provides a low reference circuit. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The IPM controls the right air temperature door position in order to maintain the selected air temperature on the right air temperature switch assembly.

The ignition is on.

The IPM detects the lower right air temperature sensor signal circuit is less than 0.09 volt or greater than 4.90 volts.

1. When the ambient air temperature is at or below 59°F (15°C), a default value of 4.80 volts will be substituted for the lower right air temperature sensor data by the IPM. The Right HTR. Duct Temp displayed on the scan tool is the default value. The Right HTR. Duct Temp displayed on the scan tool in the Open/Short Data list is the actual value.
2. When the ambient air temperature is at or above 60°F (16°C), a default value of 0.19 volt will be substituted for the sensor data by the IPM. The Right HTR. Duct Temp displayed on the scan tool is the default value. The Right HTR. Duct Temp displayed on the scan tool in the Open/Short Data list is the actual value.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe RIGHT HTR. DUCT TEMP parameter in INSTRUMENT PANEL MODULE (IPM) OPEN/SHORT data list. If scan tool indicates RIGHT HTR. DUCT TEMP parameter is .09-4.90 volts, problem is intermittent. Check wiring and connections. If scan tool indicates RIGHT HTR. DUCT TEMP parameter is not .09-4.90 volts, go to next step.
3. Turn ignition off. Disconnect lower right air temperature sensor. Turn ignition on. Using scan tool, observe RIGHT HTR. DUCT TEMP parameter. If scan tool indicates RIGHT HTR. DUCT TEMP parameter is greater than 4.90 volts, go to next step. If scan tool indicates RIGHT HTR. DUCT TEMP parameter is less than 4.0 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between lower right air temperature sensor connector terminals "A" (Black wire) and "B" (Yellow wire). Turn ignition on. Using scan tool, observe RIGHT HTR. DUCT TEMP parameter. If scan tool indicates RIGHT HTR. DUCT TEMP parameter is less than .09 volt are present, go to step 8 . If scan tool indicates RIGHT A/C DUCT TEMP parameter is greater than .09 volt are present, go to step 6 .
5. Check for a short to ground in Black wire between lower right air temperature sensor connector terminal "A" and IPM connector C1, terminal D3. Repair Black wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check for a short to voltage, high resistance or open in Black wire between lower right air temperature sensor connector terminal "A" and IPM connector C1, terminal D3. Repair Black wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check for high resistance in Yellow wire between lower right air temperature sensor connector terminal "B" and IPM connector C2, terminal B8. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check lower right air temperature sensor harness connector for poor connections. If problem was found and corrected, go to step 12 . If connections are okay, go to step 11 .
9. Check IPM harness connector for poor connections. If problem was found and corrected, go to step 12 . If connections are okay, go to step 11 .
10. Replace lower right air temperature sensor located under right side of instrument panel, on sound insulator. See «AIR TEMPERATURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B0131 does not reset, system is okay. If DTC B0131 resets, go to step 2 .

DTC B0159: AMBIENT AIR TEMPERATURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) monitors the ambient air temperature through the ambient air temperature sensor. The ambient air temperature sensor is a variable resistor. The IPM supplies 5 volts to the ambient air temperature sensor signal circuit and provides a low reference circuit. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The IPM displays the ambient air temperature on the HVAC control module.

The ignition is on.

The IPM detects the ambient air temperature sensor signal circuit is less than 0.09 volt or greater than 4.0 volts.

1. A default value of 2.50 volts will be substituted for the ambient air temperature sensor data by the IPM. The OUTSIDE AIR TEMP displayed on the scan tool is the default value. The displayed on the scan tool in the Open/Short Data list is the actual value.
2. The HVAC control module will display "- -" for ambient air temperature when off.
3. The HVAC control module will display the set temperature when on.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe OUTSIDE AIR TEMP parameter in Instrument Panel Module (IPM) open/short data list. If scan tool indicates OUTSIDE AIR TEMP parameter is .09-4.0 volts, problem is intermittent. Check wiring and connections. If scan tool indicates OUTSIDE AIR TEMP parameter is not .09-4.0 volts, go to next step.
3. Turn ignition off. Disconnect ambient air temperature sensor. Turn ignition on. Using scan tool, observe OUTSIDE AIR TEMP parameter. If scan tool indicates OUTSIDE AIR TEMP parameter is greater than 4.0 volts, go to next step. If scan tool indicates OUTSIDE AIR TEMP parameter is less than 4.0 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between ambient air temperature sensor connector terminals "A" (Light Green/Black wire) and "B" (Yellow wire). Turn ignition on. Using scan tool, observe OUTSIDE AIR TEMP parameter. If scan tool indicates OUTSIDE AIR TEMP parameter is less than .09 volt, go to step 8 . If scan tool indicates OUTSIDE AIR TEMP parameter is greater than .09 volt, go to step 6 .
5. Check Light Green/Black wire between ambient air temperature sensor connector terminal "A" and IPM connector C2, terminal B1 for a short to ground. Repair Light Green/Black wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check Light Green/Black wire between ambient air temperature sensor connector terminal "A" and IPM connector C2, terminal B1 for a short to voltage, high resistance or open. Repair Light Green/Black wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check Yellow wire between ambient air temperature sensor connector terminal "B" and IPM connector C2, terminal B8 for high resistance or open. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check ambient air temperature sensor harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 10 .
9. Check IPM harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
10. Replace ambient air temperature sensor. See «AMBIENT AIR TEMPERATURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B0159 does not reset, system is okay. If DTC B0159 resets, go to step 2 .

DTC B0164: INSIDE AIR TEMPERATURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) monitors the inside air temperature through the inside air temperature sensor. The inside air temperature sensor is a variable resistor. The IPM supplies 5 volts to the inside air temperature sensor signal circuit and provides a low reference circuit. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The IPM requests A/C compressor clutch engagement and controls the left and right air temperature door positions in order to maintain the selected air temperature on the HVAC control module.

The ignition is on.

The IPM detects the inside air temperature sensor signal circuit is less than 0.09 volt or greater than 4.0 volts.

A default value of 2.50 volts will be substituted for the inside air temperature sensor data by the IPM. The INSIDE AIR TEMP displayed on the scan tool is the default value. The INSIDE AIR TEMP displayed on the scan tool in the Open/Short Data list is the actual value.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe INSIDE AIR TEMP parameter in Instrument Panel Module (IPM) open/short data list. If scan tool indicates INSIDE AIR TEMP parameter is .9-4.0 volts, problem is intermittent. Check wiring and connections. If scan tool indicates INSIDE AIR TEMP parameter is not .9-4.0 volts, go to next step.
3. Turn ignition off. Disconnect inside air temperature sensor. Turn ignition on. Using scan tool, observe INSIDE AIR TEMP parameter. If scan tool indicates INSIDE AIR TEMP parameter is greater than 4.0 volts, go to next step. If scan tool indicates INSIDE AIR TEMP parameter is less than 4.0 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between inside air temperature sensor connector terminals "A" (Dark Green wire) and "B" (Yellow wire). Turn ignition on. Using scan tool, observe INSIDE AIR TEMP parameter. If scan tool indicates INSIDE AIR TEMP parameter is less than .09 volt, go to step 8 . If scan tool indicates INSIDE AIR TEMP parameter is greater than .09 volt, go to step 6 .
5. Check Dark Green wire between inside air temperature sensor connector terminal "A" and IPM connector C2, terminal B4 for a short to ground. Repair Dark Green wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check Dark Green wire between inside air temperature sensor connector terminal "A" and IPM connector C2, terminal B4 for a short to voltage, high resistance or open. Repair Dark Green wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check Yellow wire between inside air temperature sensor connector terminal "B" and IPM connector C2, terminal B8 for high resistance or an open. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check inside air temperature sensor harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 10 .
9. Check IPM harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
10. Replace inside air temperature sensor. See «INSIDE AIR TEMPERATURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in BODY CONTROL MODULE article. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B0164 does not reset, system is okay. If DTC B0164 resets, go to step 2 .

DTC B0174: UPPER LEFT AIR TEMPERATURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) monitors the left A/C duct air temperature through the upper left air temperature sensor. When the air is cold, the sensor resistance and signal voltage are high. The upper left air temperature sensor is a variable resistor. The IPM supplies 5 volts to the upper left air temperature sensor signal circuit and provides a low reference circuit. When the air is warm, the sensor resistance and signal voltage are low. The IPM requests A/C compressor clutch engagement and controls the left air temperature door position in order to maintain the selected air temperature on the HVAC control module.

The ignition is on.

The IPM detects the upper left air temperature sensor signal circuit is less than 0.09 volt or greater than 4.0 volts.

1. When the ambient air temperature is at or below 59°F (15°C), a default value of 4.80 volts will be substituted for the upper left air temperature sensor data by the IPM. The LEFT A/C DUCT TEMP displayed on the scan tool is the default value. The LEFT A/C DUCT TEMP displayed on the scan tool in the Open/Short Data list is the actual value.
2. When the ambient air temperature is at or above 6°F (16°C), a default value of 0.19 volt will be substituted for the upper left air temperature sensor data by the IPM. The LEFT A/C DUCT TEMP displayed on the scan tool is the default value. The LEFT A/C DUCT TEMP displayed on the scan tool in the open/short data list is the actual value.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe LEFT AC DUCT TEMP parameter in Instrument Panel Module (IPM) open/short data list. If scan tool indicates LEFT AC DUCT TEMP parameter is .09-4.0 volts, problem is intermittent. Check wiring and connections. If scan tool indicates LEFT AC DUCT TEMP parameter is not .09-4.0 volts, go to next step.
3. Turn ignition off. Disconnect upper left air temperature sensor. Turn ignition on. Using scan tool, observe LEFT AC DUCT TEMP parameter. If scan tool indicates LEFT AC DUCT TEMP parameter is greater than 4.0 volts, go to next step. If scan tool indicates LEFT AC DUCT TEMP parameter is less than 4.0 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between upper left air temperature sensor connector terminals "A" (Black wire) and "B" (Yellow wire). Turn ignition on. Using scan tool, observe LEFT AC DUCT TEMP parameter. If scan tool indicates LEFT AC DUCT TEMP parameter is less than .09 volt, go to step 8 . If scan tool indicates LEFT AC DUCT TEMP parameter is greater than .09 volt, go to step 6 .
5. Check Black wire between upper left air temperature sensor connector terminal "A" and IPM connector C2, terminal B6 for a short to ground. Repair Black wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check Black wire between upper left air temperature sensor connector terminal "A" and IPM connector C2, terminal B6 for a short to voltage, high resistance or an open. Repair Black wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check Yellow wire between upper left air temperature sensor connector terminal "B" and IPM connector C2, terminal B8 for high resistance or open. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check upper left air temperature sensor harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
9. Check IPM harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
10. Replace upper left air temperature sensor. See «AIR TEMPERATURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B0174 does not reset, system is okay. If DTC B0174 resets, go to step 2 .

DTC B0179: LOWER LEFT AIR TEMPERATURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) monitors the left heater duct air temperature through the lower left air temperature sensor. When the air is cold, the sensor resistance and signal voltage are high. The lower left air temperature sensor is a variable resistor. The IPM supplies 5 volts to the lower left air temperature sensor signal circuit and provides a low reference circuit. When the air is warm, the sensor resistance and signal voltage are low. The IPM controls the left air temperature door position in order to maintain the selected air temperature on the HVAC control module.

The ignition is on.

The IPM detects the lower left air temperature sensor signal circuit is less than 0.09 volt or greater than 4.0 volts.

1. When the ambient air temperature is at or below 59°F (15°C), a default value of 4.80 volts will be substituted for the lower left air temperature sensor data by the IPM. The LEFT HTR. DUCT TEMP displayed on the scan tool is the default value. The LEFT HTR. DUCT TEMP displayed on the scan tool in the Open/Short Data list is the actual value.
2. When the ambient air temperature is at or above 16°C (60°F), a default value of 0.19 volt will be substituted for the lower left air temperature sensor data by the IPM. The LEFT HTR. DUCT TEMP displayed on the scan tool is the default value. The LEFT HTR. DUCT TEMP displayed on the scan tool in the Open/Short Data list is the default value.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe LEFT HTR DUCT TEMP parameter in Instrument Panel Module (IPM) open/short data list. If scan tool indicates LEFT HTR DUCT TEMP parameter .09-4.0 volts, problem is intermittent. Check wiring and connections. If scan tool indicates LEFT HTR DUCT TEMP parameter is not .09-4.0 volts, go to next step.
3. Turn ignition off. Disconnect lower left air temperature sensor. Turn ignition on. Using scan tool, observe LEFT HTR DUCT TEMP parameter. If scan tool indicates LEFT HTR DUCT TEMP parameter is greater than 4.0 volts, go to next step. If scan tool indicates LEFT HTR DUCT TEMP parameter is less than 4.0 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between lower left air temperature sensor connector terminals "A" (Black wire) and "B" (Yellow wire). Turn ignition on. Using scan tool, observe LEFT HTR DUCT TEMP parameter. If scan tool indicates LEFT HTR DUCT TEMP parameter is less than .09 volt, go to step 8 . If scan tool indicates LEFT HTR DUCT TEMP parameter is greater than .09 volt, go to step 6 .
5. Check Black wire between lower left air temperature sensor connector terminal "A" and IPM connector C2, terminal B9 for a short to ground. Repair Black wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check Black wire between lower left air temperature sensor connector terminal "A" and IPM connector C2, terminal B9 for a short to voltage, high resistance or an open. Repair Black wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check Yellow wire between lower left air temperature sensor connector terminal "B" and IPM connector C2, terminal B8 for high resistance or an open. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check lower left air temperature sensor for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 10 .
9. Check IPM harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
10. Replace lower left air temperature sensor, located under left side of instrument panel, on sound insulator. See «AIR TEMPERATURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B0179 does not reset, system is okay. If DTC B0179 resets, go to step 2 .

DTC B0184 OR DTC B0189: SUNLOAD SENSOR ASSEMBLY

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The following DTCs are for the left and right sunload sensors monitored by the Instrument Panel Module (IPM)

1. B0184 - Left Sunload Sensor.
2. B0189 - Right Sunload Sensor.

The IPM monitors ambient light with the left and right sunload sensors. The sunload sensors are an infrared light sensitive photodiode. The IPM supplies 5 volts to the sunload sensors signal circuit and provides a low reference circuit. As the light shining upon the sensor gets brighter, the sensors conductance increases. The IPM uses this information to compensate for the effect of the sun on the inside air temperature of the vehicle. The IPM connects the voltage values to count values where one volt is approximately equal to 51 counts.

The ignition is on.

The IPM detects the signal circuit is less than 0.09 volt or more than 4.0 volts.

A default value of zero counts will be substituted for the sensor data by the IPM.

1. Left Sunload Sensor: The LEFT SOLAR SENSOR display on the scan tool in the HVAC sensors data list will be the default value. The LEFT SOLAR SENSOR display on the scan tool in the open/short data list will be the actual value.
2. Right Sunload Sensor: The RIGHT SOLAR SENSOR display on the scan tool in the HVAC Sensors data list will be the default value. The RIGHT SOLAR SENSOR display on the scan tool in the open/short data list will be the actual value.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 5 fault free ignition cycles.
3. The DTC can be cleared with a scan tool.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe RIGHT or LEFT SOLAR SENSOR parameter in Instrument Panel Module (IPM) open/short data list. If scan tool indicates RIGHT or LEFT SOLAR SENSOR parameter is .09-4.0 volts, problem is intermittent. Check wiring and connections. If scan tool indicates RIGHT or LEFT SOLAR SENSOR parameter is not .09-4.0 volts, go to next step.
3. Turn ignition off. Disconnect sunload sensor assembly. Turn ignition on. Using scan tool, observe RIGHT or LEFT SOLAR SENSOR parameter. If scan tool indicates RIGHT or LEFT SOLAR SENSOR parameter is greater than 4.0 volts, go to next step. If scan tool indicates RIGHT or LEFT SOLAR SENSOR parameter is less than 4.0 volts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between sunload sensor assembly connector terminal "A" (Light Blue/Black wire) or "B" (Gray wire) and sunload sensor assembly connector terminal "C" (Yellow wire). Turn ignition on, with engine off. Using scan tool, observe RIGHT or LEFT SOLAR SENSOR parameter. If scan tool indicates RIGHT or LEFT SOLAR SENSOR parameter is less than .09 volt, go to step 8 . If scan tool indicates RIGHT or LEFT SOLAR SENSOR parameter is greater than .09 volt, go to step 6 .
5. Check for a short to ground in Light Blue/Black wire between sunload sensor assembly connector terminal "A" and IPM connector C2, terminal B2, or in Gray wire between sunload sensor assembly connector terminal "B" and IPM connector C2, terminal B3. Repair Light Blue/Black or Gray wire as necessary, then go to step 12 . If circuit(s) are okay, go to step 9 .
6. Check for a short to voltage, high resistance or an open in Light Blue/Black wire between sunload sensor assembly connector terminal "A" and IPM connector C2, terminal B2, or in Gray wire between sunload sensor assembly connector terminal "B" and IPM connector C2, terminal B3. Repair Light Blue/Black or Gray wire as necessary, then go to step 12 . If circuit(s) are okay, go to next step.
7. Check for high resistance or an open in Yellow wire between sunload sensor assembly connector terminal "C" and IPM connector C2, terminal B8. Repair Yellow wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
8. Check sunload sensor assembly harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 10 .
9. Check IPM harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
10. Replace sunload sensor. See «SUNLOAD SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After replacement, go to step 12 .
11. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After replacement, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTCs B0184 or B0189 do not reset, system is okay. If DTCs B0184 or B0189 reset, go to step 2 .

DTC B0234: LEFT AIR TEMPERATURE ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) commands left air temperature actuator movement with one of 3 voltage signals applied to the left air temperature door control circuit. A low voltage of zero volts moves the left air temperature door toward full cold. A voltage of 2.5 volts stops the actuator. A voltage of 5 volts moves the left air temperature door toward full hot. The IPM determines the current position of the actuator by monitoring the feedback voltage of the left air temperature door position signal circuit. The feedback potentiometer position is a function of the actuator position. A high voltage indicates a full hot left air temperature door position. A low voltage indicates a full cold left air temperature door position. The IPM controls the left air temperature door position in order to maintain the selected air temperature on the HVAC control module.

Whenever the IPMs keep alive memory battery power is interrupted, the IPM will perform a recalibration of the actuators. During recalibration, the IPM will drive the actuators to their minimum and maximum travel extremes. The IPM will then calculate a travel range from this data, max-min range, and compare it to a calibrated range within the IPM. If the actual travel range is not within the calibrated expected range, the actuator will be considered not calibrated and the DTC will set.

1. The ignition is on.
2. The IPM power must be interrupted.
3. Perform the RECALIBRATE ALL MOTORS command using the scan tool.

The left air temperature actuator actual total travel range (max-min) is less than or greater than the calibrated limits.

1. The IPM will continue to make use of whatever left air temperature actuator travel range is still available.
2. Each time the ignition switch is turned ON the Instrument Panel Integration Module (IPM) will perform a recalibration of the actuator.

1. The left air temperature actuator travel range error must be corrected.
2. The history DTC will clear after 50 fault-free ignition cycles.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. The range fault code can only be detected following a test of the left air temperature actuator travel range. This test can only be initiated by disrupting power to the IPM, that is, by disconnecting the battery, or with the scan tool.
3. The calibration limit is 3.0-4.4 volts. An actual range below this limit suggests an obstruction, something stuck in the door limiting travel. An actual range above this limit suggests an over travel condition, damaged or missing foam seals

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe MIN LEFT TEMP DR POS and MAX LEFT TEMP DR POS parameters in Instrument Panel Module (IPM) HVAC door calibrations data list. Subtract MIN LEFT TEMP DR POS from MAX LEFT TEMP DR POS. If result of calculation indicates actual travel of left air temperature actuator is 152-20 counts, check for loose wires, poor connections or obstructions causing an intermittent. If result of calculation indicates actual travel of left air temperature actuator is not 152-20 counts, go to next step.
3. Check Brown wire between left air temperature actuator connector terminal No. 5 and HVAC (10-amp) fuse located in rear fuse block for a short to ground. Repair Brown wire as necessary, then go to step 13 . If circuit is okay, go to next step.
4. Check Dark Blue wire between left air temperature actuator connector terminal No. 6 and IPM connector C2, terminal A11 for an open, high resistance, a short to ground or short to voltage. Repair Dark Blue wire as necessary, then go to step 13 . If circuit is okay, go to next step.
5. Check Gray wire between left air temperature actuator connector terminal No. 10 and IPM connector C2, terminal A1 for an open, high resistance or short to ground. Repair Gray wire as necessary, then go to step 13 . If circuit is okay, go to next step.
6. Turn ignition on. Using scan tool, observe LEFT TEMP DR ACTUAL DATA parameter in Instrument Panel Module (IPM) HVAC door positions data list. Connect a 3-amp fused jumper wire between left air temperature connector terminals No. 6 (Dark Blue wire) and No. 10 (Gray wire) and drive actuator to full HOT position. Remove and reconnect jumper wire between left air temperature actuator connector terminals No. 6 (Dark Blue wire) and No. 7 (Yellow wire) and drive actuator to full COLD position. If left air temperature actuator drive shaft rotates and counts change, go to next step. If left air temperature actuator drive shaft does not rotate and/or counts do not change, go to step 9 .
7. Measure voltage between left air temperature actuator connector terminal No. 6 (Dark Blue wire) and a ground. Using scan tool, command LEFT TEMP DOOR position from HOT to COLD. If voltage measures near zero volt when decreasing temperature, 5 volts when increasing temperature and 2.5 volts when stationary, go to next step. If voltage does not measure near zero volt when decreasing temperature, 5 volts when increasing temperature and 2.5 volts when stationary, go to step 10 .
8. Inspect left air temperature door and actuator for misalignment, broken or binding linkages or air temperature door, obstructions preventing full range of motion, or missing/misaligned seals. Repair as necessary, then go to step 13 . If no problem was found, check for loose wires and/or poor connections causing an intermittent.
9. Inspect left air temperature actuator harness connector for poor connections. Repair as necessary, then go to step 13 . If connections are okay, go to step 11 .
10. Inspect IPM harness connector for poor connections. Repair as necessary, then go to step 13 . If connections are okay, go to step 12 .
11. Replace left air temperature actuator. See «AIR TEMPERATURE ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
12. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
13. Use scan tool to clear DTCs. Turn ignition on. Using scan tool, recalibrate all motors. See «ACTUATOR CALIBRATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS. If DTC B0234 does not reset, system is okay. If DTC B0234 resets, go to step 2 .

DTC B0237: LEFT AIR TEMPERATURE ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) commands left air temperature actuator movement with one of 3 voltage signals applied to the left air temperature door control circuit. A low voltage of zero volts moves the left air temperature door toward full cold. A voltage of 2.5 volts stops the actuator. A voltage of 5 volts moves the left air temperature door toward full hot. The IPM determines the current position of the actuator by monitoring the feedback voltage of the air temperature door position signal circuit. The feedback potentiometer position is a function of the actuator position. A high voltage indicates a full hot left air temperature door position. A low voltage indicates a full cold left air temperature door position. The IPM controls the left air temperature door position in order to maintain the selected air temperature on the HVAC control module.

The IPM will perform a continuous test on the current feedback voltage. If the feedback voltage does not equal or fall within the calibrated limits, the DTC will set.

The ignition is on.

The IPM detects the signal circuit is less than 0.05 volt or greater than 4.0 volts.

1. A default value of 2.50 volts will be substituted for the left air temperature door position data by the IPM.
2. The IPM will toggle the actuator between full hot and full cool in an attempt to maintain the selected air temperature on the HVAC control module.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. A damaged or broken air temperature door and or actuator can cause this DTC to set by allowing the actuator shaft to rotate unrestricted to its internal stop, creating an overtravel condition. The internal stops are outside of the feedback potentiometers zero-250 count working range.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe LEFT TEMP DR ACTUAL parameter in instrument panel module data list. If scan tool indicates LEFT TEMP DR ACTUAL parameter is .05-4.0 volts, problem is intermittent. Check for loose wires, poor connections or obstruction causing an intermittent. If scan tool indicates LEFT TEMP DR ACTUAL parameter is not .05-4.0 volts, go to next step.
3. Using scan tool, command LEFT TEMP DR from HOT to COLD position. Using scan tool, observe LEFT TEMP DR ACTUAL parameter in instrument panel module data list. If scan tool indicates LEFT TEMP DR ACTUAL parameter changes when door is commanded from hot to cold, go to step 12 . If scan tool indicates LEFT TEMP DR ACTUAL parameter does not change when door is commanded from hot to cold, go to next step.
4. Turn ignition off. Disconnect left air temperature actuator. Turn ignition on. Using scan tool, observe LEFT TEMP DR ACTUAL parameter. If scan tool indicates LEFT TEMP DR ACTUAL parameter is greater than 4.0 volts, go to next step. If scan tool indicates LEFT TEMP DR ACTUAL parameter is less than 4.0 volts, go to step 9 .
5. Turn ignition off. Connect 3-amp fused jumper wire between left air temperature actuator connector terminals No. 9 (Light Blue wire) and No. 7 (Yellow wire). Turn ignition on. Using scan tool, check LEFT TEMP DR ACTUAL parameter. If scan tool indicates LEFT TEMP DR ACTUAL parameter is less than .05 volt, go to next step. If scan tool indicates LEFT TEMP DR ACTUAL parameter is greater than .05 volt, go to step 10 .
6. Turn ignition off. Disconnect fused jumper wire. Connect 3-amp fused jumper wire between left air temperature actuator connector terminals No. 9 (Light Blue wire) and No. 10 (Gray wire). Using scan tool, observe LEFT TEMP DR ACTUAL parameter. If scan tool indicates LEFT TEMP DR ACTUAL parameter is greater than 4.9 volts, go to step 8 . If scan tool indicates LEFT TEMP DR ACTUAL parameter is less 4.9 volts, go to next step.
7. Check Gray wire between left air temperature actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to ground. Repair Gray wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
8. Check Gray wire between left air temperature actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to voltage, high resistance or an open. Repair Gray wire as necessary, then go to step 17 . If circuit is okay, go to step 13 .
9. Check Light Blue wire between left air temperature actuator connector terminal No. 9 and IPM connector C2, terminal A11 for a short to ground. Repair Light Blue wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
10. Check Light Blue wire between left air temperature actuator connector terminal No. 9 and IPM connector C2, terminal A11 for a short to voltage, high resistance or an open. Repair Light Blue wire as necessary, then go to step 17 . If circuit is okay, go to next step.
11. Check Yellow wire between left air temperature actuator connector terminal No. 7 and IPM connector C2, terminal A7 for high resistance or an open. Repair Yellow wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
12. Check left air temperature actuator for condition allowing excessive travel of actuator. Repair as necessary, then go to step 17 . If actuator is okay, go to next step.
13. Check left air temperature actuator harness connector for poor connections. Repair as necessary, then go to step 17 . If connections are okay, go to step 15 .
14. Check IPM harness connector for poor connections. Repair as necessary, then go to step 17 . If connections are okay, go to step 16 .
15. Replace left air temperature actuator located at air mix door. See «AIR TEMPERATURE ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
16. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
17. Use scan tool to clear DTCs. Turn ignition on. If DTC B0237 does not reset, system is okay. If DTC B0237 resets, go to step 2 .

DTC B0249: MODE ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The Instrument Panel Integration Module (IPM) controls the mode door position by sending a control signal to the actuator. The signals value is dependent upon the desired mode selected by the vehicle occupants. The control signal is near zero volts when the mode actuator is commanded toward the defrost position, near 5 volts when commanded toward the VENT position, and near 2.5 volts when stationary. As the mode actuator moves, the potentiometer produces the actual door position signal that is sent to the IPM. The IPM continues to command the actuator to move until the desired and actual values are equal.

When a calibration or recalibration procedure is performed, the IPM calculates the mode door travel range. The IPM commands the actuator through its full range. The IPM stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum position value from the maximum position value. The IPM compares the travel range to calibrated limits. If the travel range value is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful. The IPM continuously compares the actual actuator position to the calibrated minimum and maximum position values.

1. The range fault code can only be set following a calibration/recalibration of the mode actuator.
2. The IPM will not perform a calibration/recalibration of the mode actuator if DTC B0252 is set as current.

The actual total travel range of the mode door (max-min) is less than 00 counts or greater than 246 counts.

1. The IPM will continue to make use of whatever travel range is still available.
2. The IPM will recalibrate the mode door travel range each time the ignition switch is turned ON.

1. A successful recalibration of the mode door must be completed.
2. A history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. The calibration limit is 3.9-4.8 volts. An actual range below this limit suggests an obstruction of the mode door or a binding linkage limiting travel. An actual range above this limit suggests an over travel condition (damaged or missing foam seals).

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe MIN HTR, DEF, A/C DR POS and MAX HTR, DEF, A/C DR POS parameters in Instrument Panel Module (IPM) data list. Subtract value of MIN HTR, DEF, A/C DR POS parameter from value of MAX HTR, DEF, A/C DR POS parameter. If result of calculation indicates travel range of mode door is within 3.9-4.8 volts, check for loose wire, poor connections or door obstruction causing an intermittent. If result of calculation indicates travel range of mode door is not within 3.9-4.8 volts, go to next step.
3. If calculation indicates travel range of mode door is greater than .3 volts, go to step 10 . If counts are less than .3 volts, go to next step.
4. Turn ignition off. Disconnect mode actuator. Turn ignition on. Using a test light connected to ground, probe Brown wire at mode actuator connector terminal No. 5. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
5. Measure voltage between Gray wire at mode actuator connector terminal No. 10 and ground. If voltage is near 5 volts, go to next step. If voltage is not near 5 volts, go to step 9 .
6. Turn ignition off. Turn ignition on. Measure voltage between Yellow wire at mode actuator connector terminal No. 6 and ground. If voltage measures approximately 2.3-2.7 volts, go to step 8 . If voltage does not measure approximately 2.3-2.7, go to next step.
7. Check Yellow wire between mode actuator connector terminal No. 6 and IPM connector C2, terminal A8 for an open, short to ground or short to voltage. Repair Yellow wire as necessary, then go to step 16 . If circuit is okay, go to step 12 .
8. Turn ignition off. Connect mode actuator connector. Turn ignition on. Using scan tool, observe HTR, DEF, A/C DR ACTUAL parameter in instrument panel module HVAC door positions data list. Connect 3-amp fused jumper wire between mode actuator connector terminals No. 6 (Yellow wire) and No. 10 (Gray wire), driving actuator toward vent position. Remove and reconnect jumper wire between mode actuator connector terminals No. 6 (Yellow wire) and No. 7 (Yellow wire), driving actuator toward DEFROST position. If scan tool indicates total travel range of mode door is greater than 15 counts, go to step 12 . If scan tool indicates total travel range of mode door is less than 15 counts, go to step 10 .
9. Check Gray wire between mode actuator connector terminal No. 10 and IPM connector C2, terminal A1 or an open or short to ground. Repair Gray wire as necessary, then go to step 16 . If circuit is okay, go to step 12 .
10. Check mode door and mode actuator for misalignment, broken or binding linkages or mode door, obstruction preventing full range of motion, and missing/misaligned seals. Repair as necessary, then go to step 16 . If components are okay, go to next step.
11. Check mode actuator harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 14 .
12. Check IPM harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 15 .
13. Repair open in Brown wire between mode actuator connector terminal No. 5 and HVAC (10-amp) fuse located in rear fuse block. After repairs are complete, go to step 16 .
14. Replace mode actuator. See «MODE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 16 .
15. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
16. Use scan tool to clear DTCs. Using scan tool, recalibrate actuator. See «ACTUATOR CALIBRATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS. If DTC B0249 does not reset, system is okay. If DTC B0249 resets, go to step 2 .

DTC B0252: MODE ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The mode actuator is an electronic stepper motor with a feedback potentiometer. The Instrument Panel Integration Module (IPM) determines the position of the mode door based on the voltage from the potentiometer. When the airflow is from the vent outlet, the voltage is high. When the airflow is from the defrost outlet, the voltage is low. The IPM controls the mode door position to direct airflow from the outlets selected by the vehicle occupants.

The ignition is on.

The IPM detects the mode door position signal is less than 0.1 volts or greater than 4.9 volts.

1. The IPM will only direct airflow from either the vent or defrost outlets.
2. If B0252 sets during a calibration/recalibration event, the IPM will no longer issue commands to the actuator and will not perform a calibration/recalibration until the door position feedback fault is corrected.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. A disconnected or broken door/linkage may also set this DTC during calibration/recalibration by allowing the actuator to travel to its minimum internal stop, creating an over travel condition.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe HTR, DEF, A/C DR ACTUAL parameter in instrument panel module data list. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is within .25-4.9 volts, check for loose wires, poor connections or obstructed door causing an intermittent. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is not within .25-4.9 volts, go to next step.
3. Turn ignition off. Disconnect mode actuator. Turn ignition on. Using scan tool, observe HTR, DEF, A/C DR ACTUAL parameter. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is greater than 4.9 volts, go to next step. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is less than 4.9 volts, go to step 8 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between mode actuator connector terminals. No. 9 (Yellow/Black wire) and No. 7 (Yellow wire). Turn ignition on. Using scan tool, observe HTR, DEF, A/C DR ACTUAL parameter. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is less than .25 volts, go to next step. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is greater than .25 volts, go to step 9 .
5. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between mode actuator connector terminals No. 10 (Gray wire) and No. 9 (Yellow/Black wire). Turn ignition on. Using scan tool, observe HTR, DEF, A/C DR ACTUAL parameter. If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is greater than 4.9 volts, go to step 7 . If scan tool indicates HTR, DEF, A/C DR ACTUAL parameter is less than 4.9 volts, go to next step.
6. Check Gray wire between mode actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to ground. Repair Gray wire as necessary, then go to step 16 . If circuit is okay, go to step 13 .
7. Check for a short to voltage, high resistance, or an open in Gray wire between mode actuator connector terminal No. 10 and IPM connector C2, terminal A1. Repair Gray wire as necessary, then go to step 16 . If circuit is okay, go to step 11 .
8. Check Yellow/Black wire between mode actuator connector terminal No. 9 and IPM connector C2, terminal A2 for a short to ground. Repair Yellow/Black wire as necessary, then go to step 16 . If circuit is okay, go to step 13 .
9. Check Yellow/Black wire between mode actuator connector terminal No. 9 and IPM connector C2, terminal A2 for a short to voltage, high resistance, or an open. Repair Yellow/Black wire as necessary, then go to step 16 . If circuit is okay, go to next step.
10. Check Yellow wire between mode actuator connector terminal No. 7 and IPM connector C2, terminal A7 for high resistance or an open. Repair Yellow wire as necessary, then go to step 16 . If circuit is okay, go to step 13 .
11. Check mode door and mode actuator for misalignment, broken or binding linkages, obstruction preventing full range of motion, or missing/misaligned seals. Repair as necessary, then go to step 16 . If components are okay, go to next step.
12. Check mode actuator harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 14 .
13. Check IPM harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 15 .
14. Replace mode actuator. See «MODE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 16 .
15. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
16. Use scan tool to clear DTCs. Turn ignition on. If DTC B0252 does not reset, system is okay. If DTC B0252 resets, go to step 2 .

DTC B0269: RECIRCULATION ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The recirculation actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The Instrument Panel Integration Module (IPM) controls the recirculation door position by sending a control signal to the actuator. The signals value is dependent upon the desired setting selected by the vehicle occupants. The control signal is near zero volts when the recirculation actuator is commanded toward the outside air position, near 5 volts when commanded toward the recirculation position, and near 2.5 volts when stationary. As the recirculation actuator moves, the potentiometer produces the actual door position signal that is sent to the IPM. The IPM continues to command the actuator to move until the desired and actual values are equal.

When a calibration or recalibration procedure is performed, the IPM calculates the recirculation door travel range. The IPM commands the actuator through its full range. The IPM stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum position value from the maximum position value. The IPM compares the travel range to calibrated limits. If the travel range value is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful. The IPM continuously compares the actual actuator position to the calibrated minimum and maximum position values.

The IPM will not perform a calibration/recalibration of the recirculation actuator if DTC B0272 is set as current.

The actual total travel range of the recirculation door, max-min, is less than 2.9 volts or greater than 4.3 volts.

1. The IPM will continue to make use of whatever travel range is still available.
2. The IPM will recalibrate the recirculation door travel range each time the ignition switch is turned ON.

1. A successful recalibration of the recirculation door must be completed.
2. A history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. The calibration limit is 2.9-4.3 volts. An actual range below this limit suggests an obstruction of the recirculation door or a binding linkage limiting travel. An actual range above this limit suggests an over travel condition damaged or missing foam seals.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Using scan tool, observe MIN AIR INLET DR POS and MAX AIR INLET DR POS parameters in instrument panel module data list. Subtract value of MIN AIR INLET DR POS parameter from value of MAX AIR INLET DR POS parameter. If result of calculation indicates total travel of recirculation door is within 2.9-4.3 volts, check for loose wires, poor connections or obstructed door causing an intermittent. If result of calculation indicates total travel of recirculation door is not within 2.9-4.3 volts, go to next step.
3. If result of calculation indicates total travel range of recirculation door is greater than .3 volt, go to step 10 . If total travel range of recirculation door is less than .3 volt go to next step.
4. Turn ignition off. Disconnect recirculation actuator. Turn ignition on. Using a test light connected to ground, probe Brown wire at recirculation actuator connector terminal No. 5. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
5. Measure voltage between Gray wire at recirculation actuator connector terminal No. 10 and ground. If voltage measures near 5 volts, go to next step. If voltage does not measure near 5 volts, go to step 9 .
6. Turn ignition off. Turn ignition on. Measure voltage between Dark Green wire at recirculation actuator connector terminal No. 6 and ground. If voltage measures approximately 2.3-2.7 volts, go to step 8 . If voltage does not measure approximately 2.3-2.7 volts, go to next step.
7. Check Dark Green wire between recirculation actuator connector terminal No. 6 and IPM connector C2, terminal A10 for an open, short to ground or short to voltage. Repair Dark Green wire as necessary, then go to step 16 . If circuit is okay, go to step 12 .
8. Turn ignition off. Connect recirculation actuator connector. Turn ignition on. Using scan tool, observe AIR INLET DR ACTUAL parameter in instrument panel module HVAC door positions data list. Connect 3-amp fused jumper wire between recirculation actuator connector terminals No. 6 (Dark Green wire) and No. 10 (Gray wire), driving actuator toward RECIRCULATION position. Remove and reconnect jumper wire between mode actuator connector terminals No. 6 (Dark Green wire) and No. 7 (Yellow wire), driving actuator toward outside air position. If scan tool indicates total travel range of recirculation door is greater than 15 counts, go to step 12 . If scan tool indicates total travel range of recirculation door is less than 15 counts, go to step 10 .
9. Check Gray wire between recirculation actuator connector terminal No. 10 and IPM connector C2, terminal A1 for an open or short to ground. Repair Gray wire as necessary, then go to step 16 . If circuit is okay, go to step 12 .
10. Check recirculation door and recirculation actuator for misalignment, broken or binding linkages, obstruction preventing full range of motion, or missing/misaligned seals. Repair as necessary, then go to step 16 . If components are okay, go to next step.
11. Check recirculation actuator harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 14 .
12. Check IPM harness connector for poor connections. Repair as necessary, then go to step 16 . If circuit is okay, go to step 15 .
13. Repair Brown wire between recirculation actuator connector terminal No. 5 and HVAC (10-amp) fuse located in rear fuse block. After repairs are complete, go to step 16 .
14. Replace recirculation actuator. See «RECIRCULATION ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 16 .
15. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
16. Use scan tool to clear DTCs. Using scan tool, recalibrate actuator. See «ACTUATOR CALIBRATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS. If DTC B0269 does not reset, system is okay. If DTC B0269 resets, go to step 2 .

DTC B0272: RECIRCULATION ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The recirculation actuator is an electronic stepper motor with a feedback potentiometer. The Instrument Panel Integrated Module (IPM) determines the position of the recirculation door based on the voltage from the potentiometer. When the airflow is being recirculated, the voltage is low. When outside air is being admitted, voltage is high. The IPM controls the recirculation door in either the recirculation or the outside air position as selected by the vehicle occupants.

The ignition is on.

The IPM detects the recirculation door position signal is less than 0.1 volt or greater than 4.9 volts.

1. The recirculation door will be set to the OUTSIDE AIR position.
2. If B0272 sets during a calibration/recalibration event, the IPM will no longer issue commands to the actuator and will not perform a calibration/recalibration until the door position feedback fault is corrected.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. A disconnected or broken door/linkage may also set this DTC during calibration/recalibration by allowing the actuator to travel to its minimum internal stop, creating an over travel condition.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe AIR INLET DR ACTUAL parameter in instrument panel module data list. If scan tool indicates AIR INLET DR ACTUAL parameter is within .25-4.9 volts, check for loose wires, poor connections or door obstruction causing an intermittent. If scan tool indicates AIR INLET DR ACTUAL parameter is not within .25-4.9 volts, go to next step.
3. Turn ignition off. Disconnect recirculation actuator. Turn ignition on. Using scan tool, observe AIR INLET DR ACTUAL parameter. If scan tool indicates AIR INLET DR ACTUAL parameter is greater than 4.9 volts, go to next step. If scan tool indicates AIR INLET DR ACTUAL parameter is less than 4.9 volts, go to step 8 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between recirculation actuator connector terminals No. 9 (Purple wire) and No. 7 (Yellow wire). Turn ignition on. Using scan tool, observe AIR INLET DR ACTUAL parameter. If scan tool indicates AIR INLET DR ACTUAL parameter is less than .25 volts, go to next step. If scan tool indicates AIR INLET DR ACTUAL parameter is greater than .25 volts, go to step 9 .
5. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between recirculation actuator connector terminals No. 10 (Gray wire) and No. 9 (Purple wire). Turn ignition on. Using scan tool, observe AIR INLET DR ACTUAL parameter. If scan tool indicates AIR INLET DR ACTUAL parameter is greater than 4.9 volts, go to step 7 . If scan tool indicates AIR INLET DR ACTUAL parameter is less than 250 counts (4.9 volts), go to next step.
6. Check Gray wire between recirculation actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to ground. Repair Gray wire as necessary, then go to step 16 . If circuit is okay, go to step 13 .
7. Check Gray wire between recirculation actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to voltage, high resistance, or an open. Repair Gray wire as necessary, then go to step 16 . If circuit is okay, go to step 11 .
8. Check Purple wire between recirculation actuator connector terminal No. 9 and IPM connector C2, terminal A4 for a short to ground. Repair Purple wire as necessary, then go to step 16 . If circuit is okay, go to step 13 .
9. Check Purple wire between recirculation actuator connector terminal No. 9 and IPM connector C2, terminal A4 for a short to voltage, high resistance, or an open. Repair Purple wire as necessary, then go to step 16 . If circuit is okay, go to next step.
10. Check Yellow wire between recirculation actuator connector terminal No. 7 and IPM connector C2, terminal A7 for high resistance or an open. Repair Yellow wire as necessary, then go to step 16 . If circuit is okay, go to step 13 .
11. Check recirculation door and recirculation actuator for misalignment, broken or binding linkages, obstruction preventing full range of motion, or missing/misaligned seals. Repair as necessary, then go to step 16 . If components are okay, go to next step.
12. Check recirculation actuator harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 14 .
13. Check IPM harness connector for poor connections. Repair as necessary, then go to step 16 . If connections are okay, go to step 15 .
14. Replace recirculation actuator. See «RECIRCULATION ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs, go to step 16 .
15. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
16. Use scan tool to clear DTCs. Turn ignition on. If DTC B0272 does not reset, system is okay. If DTC B0272 resets, go to step 2 .

DTC B0279: RIGHT AIR TEMPERATURE ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) commands right air temperature actuator movement with one of 3 voltage signals applied to the right air temperature door control circuit. A low voltage of zero volts moves the right air temperature door toward full hot. A voltage of 2.5 volts stops the actuator. A voltage of 5 volts moves the right air temperature door toward full cold. The IPM determines the current position of the actuator by monitoring the feedback voltage of the right air temperature door position signal circuit. The feedback potentiometer position is a function of the actuator position. A high voltage indicates a full cold right air temperature door position. A low voltage indicates a full hot right air temperature door position. The IPM controls the right air temperature door position in order to maintain the selected air temperature on the HVAC control module.

Whenever the IPMs keep alive memory battery power is interrupted, the IPM will perform a recalibration of the actuators. During recalibration, the IPM will drive the actuators to their minimum and maximum travel extremes. The IPM will then calculate a travel range from this data, max-min range, and compare it to a calibrated range within the IPM. If the actual travel range is not within the calibrated expected range, the actuator will be considered not calibrated and the DTC will set.

1. The ignition is on.
2. The IPM power must be interrupted.
3. Perform the RECALIBRATE ALL MOTORS command using the scan tool.

The right air temperature actuator actual total travel range (max-min) is less than or greater than the calibrated limits.

1. The IPM will continue to make use of whatever right air temperature actuator travel range is still available.
2. Each time the ignition switch is turned ON, the Instrument Panel Integration Module (IPM) will perform a recalibration of the actuator.

1. The right air temperature actuator travel range error must be corrected.
2. The history DTC will clear after 50 fault-free ignition cycles.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. The range fault code can only be detected following a test of the right air temperature actuator travel range. This test can only be initiated by disrupting power to the IPM, that is, by disconnecting the battery or with the scan tool.
3. The calibration limit is 2.9-4.4 volts actual range below this limit suggests an obstruction, something stuck in the door limiting travel. An actual range above this limit suggests an over travel condition, damaged or missing foam seals.

Diagnostic Procedure

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe MIN RIGHT TEMP DR POS and MAX RIGHT TEMP DR POS parameters in instrument panel module HVAC doors calibrations data list. Subtract MIN RIGHT TEMP DR POS from MAX RIGHT TEMP DR POS. If result of calculation indicates actual travel of right air temperature actuator is within 147-20 counts, check for loose wires, poor connections or door obstruction causing an intermittent. If result of calculation indicates actual travel of right air temperature actuator is not within 147-20 counts, go to next step.
3. Check Brown wire between right air temperature actuator connector terminal No. 5 and HVAC (10-amp) fuse located in rear fuse block for an open or high resistance. Repair Brown wire as necessary, then go to step 13 . If circuit is okay, go to next step.
4. Check White/Black wire between right air temperature actuator connector terminal No. 6 and IPM connector C2, terminal A12 for an open, high resistance, short to ground or short to voltage. Repair White/Black wire as necessary, then go to step 13 . If circuit is okay, go to next step.
5. Check Gray wire between right air temperature actuator connector terminal No. 10 and IPM connector C2, terminal A1 for an open or high resistance. Repair Gray wire as necessary, then go to step 13 . If circuit is okay, go to next step.
6. Turn ignition on. Using scan tool, observe RIGHT TEMP DR ACTUAL data parameter in instrument panel module HVAC door positions data list. Connect a 3-amp fused jumper wire between right air temperature actuator connector terminals No. 6 (White/Black wire) and No. 10 (Gray wire), driving actuator to full cool. Remove and reconnect jumper wire between right air temperature actuator connector terminals No. 6 (White/Black wire) and No. 7 (Yellow wire), driving actuator to full hot. If air temperature actuator drive shaft rotates and counts change, go to next step. If air temperature actuator drive shaft does not rotate and counts do not change, go to step 9 .
7. Measure voltage between White/Black wire at right air temperature actuator connector terminal No. 6 and ground. Using scan tool, command RIGHT TEMP DOOR POSITION from HOT to COLD. If voltage measures near zero volts when increasing temperature, 5 volts when decreasing temperature, and 2.5 volts when stationary, go to next step. If voltage does not measure near zero volts when increasing temperature, 5 volts when decreasing temperature, and 2.5 volts when stationary, go to step 10 .
8. Check right air temperature door and actuator for misalignment, broken or binding linkages, obstruction preventing full range of motion, or missing/misaligned seals. Repair as necessary, then go to step 13 . If components are okay, problem is intermittent. Check wiring and connections.
9. Check right air temperature actuator harness connector for poor connections. Repair as necessary, then go to step 13 . If connections are okay, go to step 11 .
10. Check IPM harness connector for poor connections. Repair as necessary, then go to step 13 . If connections are okay, go to step 12 .
11. Replace right air temperature actuator. See «AIR TEMPERATURE ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
12. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
13. Use scan tool to clear DTCs. Recalibrate actuator. See «ACTUATOR CALIBRATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS. Turn ignition on. If DTC B0279 does not reset, system is okay. If DTC B0279 resets, go to step 2 .

DTC B0282: RIGHT AIR TEMPERATURE ACTUATOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) commands right air temperature actuator movement with one of 3 voltage signals applied to the right air temperature door control circuit. A low voltage of zero volts moves the right air temperature door toward full hot. A voltage of 2.5 volts stops the actuator. A voltage of 5 volts moves the right air temperature door toward full cold. The IPM determines the current position of the actuator by monitoring the feedback voltage of the right air temperature door position signal circuit. The feedback potentiometer position is a function of the actuator position. A high voltage indicates a full cold right air temperature door position. A low voltage indicates a full hot right air temperature door position. The IPM controls the right air temperature door position in order to maintain the selected air temperature on the HVAC control module.

The IPM will perform a continuous test on the current feedback voltage. If the feedback voltage does not equal or fall within the calibrated limits, the DTC will set.

The ignition is on.

The IPM detects the signal circuit is less than 0.09 volt or greater than 4.90 volts.

1. A default value of 2.50 volts will be substituted for the right air temperature door position data by the IPM.
2. The IPM will toggle the actuator between full hot and full cool in an attempt to maintain the selected air temperature on the HVAC control module.

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. A damaged or broken right air temperature door and or actuator can cause this DTC to set by allowing the actuator shaft to rotate unrestricted to its internal stop, creating an overtravel condition. The internal stops are outside of the feedback potentiometers zero-250 count working range.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter in instrument panel module HVAC door positions data list. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is .09-4.9 volts, problem is intermittent. Check wiring and connections. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is not .09-4.9 volts, go to next step.
3. Using scan tool, command RIGHT TEMP DR position from ON to OFF. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates RIGHT TEMP DR ACTUAL parameter changes when door is commanded from ON to OFF, go to step 12 . If scan tool indicates RIGHT TEMP DR ACTUAL parameter does not change when door is commanded from ON to OFF, go to next step.
4. Turn ignition off. Disconnect right air temperature actuator. Turn ignition on. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is greater than 4.0 volts, go to next step. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is less than 4.0 volts, go to step 9 .
5. Turn ignition off. Connect a 3-amp fused jumper wire between right air temperature actuator connector terminals No. 9 (Dark Blue wire) and No. 7 (Yellow wire). Turn ignition on. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is less than .09 volt, go to next step. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is greater than .09 volt, go to step 10 .
6. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between right air temperature actuator connector terminals No. 9 (Dark Blue wire) and No. 10 (Gray wire). Turn ignition on. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates RIGHT TEMP DR ACTUAL parameter is greater than 4.9 volts, go to step 8 . If scan tool indicates RIGHT TEMP DR ACTUAL parameter is less than 4.9 volts, go to next step.
7. Check Gray wire between right air temperature actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to ground. Repair Gray wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
8. Check Gray wire between right air temperature actuator connector terminal No. 10 and IPM connector C2, terminal A1 for a short to voltage, high resistance or an open. Repair Gray wire as necessary, then go to step 17 . If circuit is okay, go to step 13 .
9. Check Dark Blue wire between right air temperature actuator connector terminal No. 9 and IPM connector C2, terminal A6 for a short to ground. Repair Dark Blue wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
10. Check Dark Blue wire between right air temperature actuator connector terminal No. 9 and IPM connector C2, terminal A6 for a short to voltage, high resistance or an open. Repair Dark Blue wire as necessary, then go to step 17 . If circuit is okay, go to next step.
11. Check Yellow wire between right air temperature actuator connector terminal No. 7 and IPM connector C2, terminal A7 for high resistance or an open. Repair Yellow wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
12. Check right air temperature door for excessive travel of actuator. Repair as necessary, then go to step 17 . If components are okay, go to next step.
13. Check right air temperature actuator harness connector for poor connections. Repair as necessary, then go to step 17 . If connections are okay, go to step 15 .
14. Check IPM harness connector for poor connections. Repair as necessary, then go to step 17 . If connections are okay, go to step 16 .
15. Replace right air temperature actuator. See «AIR TEMPERATURE ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
16. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
17. Use scan tool to clear DTCs. Turn ignition on. If DTC B0282 does not reset, system is okay. If DTC B0282 resets, go to step 2 .

DTC B0490: RIGHT AIR TEMPERATURE SWITCH ASSEMBLY

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The right air temperature switch assembly consists of simple momentary contact switches that connect a series of resistors so that each switch selection corresponds to a fixed resistance value. The Front Passenger Door Module (FPDM) determines which switch has been pressed by the voltage drop across the corresponding resistance value. The FPDM converts this input to a digital signal and communicates it to the Driver Door Module (DDM) over the simple bus interface (SBI). The DDM is responsible for the class 2 interface and setting the DTC.

The ignition is on.

1. The DDM detects that the right air temperature switch signal circuit of the right air temperature switch assembly is less than 0.09 volt or greater than 4.90 volts.
2. The DDM detects that the right air temperature switch assembly is active for more than 30 seconds.

The DDM will ignore the switch command.

1. The DTC will become history if the DDM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.
2. When the warmer (Red) switch is active, the input to the DDM is 2.50-3.09 volts.
3. When the cooler (Blue) switch is active, the input to the DDM is 0.99-1.58 volts.
4. When neither switch is active, the input to the DDM is 3.99-4.58 volts.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe PASS HVAC SWITCH parameter in driver door module data list. If scan tool indicates PASS HVAC SWITCH parameter is 4-234 counts, neither switch is active, and input to Driver Door Module (DDM) is 3.99-4.58 volts. Check for loose wires and/or poor connections causing an intermittent. If scan tool indicates PASS HVAC SWITCH parameter is not 4-234 counts, go to next step.
3. Turn ignition off. Disconnect right air temperature switch assembly. Turn ignition on. Using scan tool, observe PASS HVAC SWITCH parameter. If scan tool indicates PASS HVAC SWITCH parameter is greater than 250 counts, go to next step. If scan tool indicates PASS HVAC SWITCH parameter is less than 250 counts, go to step 5 .
4. Turn ignition off. Connect a 3-amp fused jumper wire between right air temperature switch assembly connector terminals No. 8 (Pink wire) and No. 14 (Purple wire). Turn ignition on. Using scan tool, observe PASS HVAC SWITCH parameter. If scan tool indicates PASS HVAC SWITCH parameter is less than 5 counts, go to step 8 . If scan tool indicates PASS HVAC SWITCH parameter is 5 counts or more, go to step 6 .
5. Check Pink wire between right air temperature switch assembly connector terminal No. 8 and Front Passenger Door Module (FPDM) connector C1, terminal No. 2 for a short to ground. Repair Pink wire as necessary, then go to step 12 . If circuit is okay, go to step 9 .
6. Check Pink wire between right air temperature switch assembly connector terminal No. 8 and Front Passenger Door Module (FPDM) connector C1, terminal No. 2 for a short to voltage, high resistance, or an open. Repair Pink wire as necessary, then go to step 12 . If circuit is okay, go to next step.
7. Check Purple wire between right air temperature switch assembly connector assembly terminal No. 14 and FPDM connector C1, terminal No. 3 for high resistance or an open. Repair Purple wire as necessary, then go to step 12 . If circuit is okay, is okay, go to step 9 .
8. Check right air temperature switch assembly harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 10 .
9. Check FPDM harness connector for poor connections. Repair as necessary, then go to step 12 . If connections are okay, go to step 11 .
10. Replace right air temperature switch assembly. See «AIR TEMPERATURE SWITCH»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
11. Replace FPDM. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
12. Use scan tool to clear DTCs. Turn ignition on. If DTC B040 does not reset, system is okay. If DTC B040 resets, go to step 2 .

DTC B1000: ECU MALFUNCTION

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Instrument Panel Integration Module (IPM) communicates with the HVAC control module through the HVAC control module assembly data signal and HVAC control module clock signal. This communication link is only used by the IPM and the HVAC control module.

The ignition is on.

1. There is a loss of communications between the IPM and the HVAC control module.
2. The above conditions are present for 3 seconds.

The HVAC system will be disabled.

DTC

1. The DTC will become history if the IPM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Observe HVAC control module display. If all visual indicators are illuminated and audible indicator is on, go to step 7 . If visual indicator is not illuminated and audible indicator is not on, go to next step.
3. Observe HVAC control module display. If display is blank, go to step 5 . If display is not blank, go to next step.
4. Observe HVAC control module display. If HVAC control module displays only °C and °F, go to step 8 . If HVAC control module does not only display °C and °F, problem is intermittent. Check wiring and connectors.
5. Turn ignition off. Disconnect HVAC control module. Turn ignition on. Using a test light connected to ground, probe Brown wire at HVAC control module connector terminal A2. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
6. Connect a test light between HVAC control module connector terminals A2 (Brown wire) and A1 (Black wire). If test light illuminates, go to step 15 . If test light does not illuminate, go to step 11 .
7. Turn ignition off. Disconnect HVAC control module. Turn ignition on. Measure voltage of Light Blue wire between HVAC control module connector terminal B6 and ground. If voltage measures near one volt, go to step 15 . If voltage does not measure near one volt, go to step 12 .
8. Turn ignition off. Disconnect HVAC control module. Turn ignition on. Measure voltage of Light Blue wire between HVAC control module connector terminal B6 and ground. If voltage measures near one volt, go to next step. If voltage does not measure near one volt, go to step 13 .
9. Measure frequency of Purple wire between HVAC control module connector terminal B5 and ground. If frequency measures near 930 Hertz, go to step 15 . If frequency does not measure near 930 Hertz, go to step 14 .
10. Repair short to ground, high resistance, or an open circuit in Brown wire between HVAC control module connector terminal A2 and IGN 3 (10-amp) fuse located in rear fuse block. After repair, go to step 19 .
11. Repair high resistance or open in Black wire at HVAC control module connector terminal A1. After repair, go to step 19 .
12. Check Light Blue wire between HVAC control module connector terminal B6 and IPM connector C1, terminal C12 for a short to voltage or an open. Repair Light Blue wire as necessary, then go to step 19 . If circuit is okay, go to step 16 .
13. Check Light Blue wire between HVAC control module connector terminal B6 and IPM connector C1, terminal C12 for a short to ground. Repair Light Blue wire as necessary, then go to step 19 . If circuit is okay, go to next step.
14. Check Purple wire between HVAC control module connector terminal B5 and IPM connector C1, terminal C13 for a short to voltage, short to ground, or an open. Repair Light Blue wire as necessary, then go to step 19 . If circuit is okay, go to step 16 .
15. Check HVAC control module harness connector for poor connections. Repair as necessary, then go to step 19 . If connections are okay, go to step 17 .
16. Check IPM harness connector for poor connections. Repair as necessary, then go to step 19 . If connections are okay, go to step 18 .
17. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 19 .
18. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
19. Use scan tool to clear DTCs. Turn ignition on. If DTC B1000 does not reset, system is okay. If DTC B1000 resets, go to step 2 .

DTC B2805: STEERING WHEEL CONTROLS

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The steering wheel controls are simple momentary contact switches that connect a series of resistors so that each switch selection corresponds to a fixed resistance value. The Dash Integration Module (DIM) determines which switch has been pressed by the voltage drop across the corresponding resistance value.

The DIM must be powered.

One of the temperature switches must be active for more than 30 seconds.

The DIM will disable all of the steering wheel control switches while the fault is present.

1. The DTC will become history if the DIM no longer detects a failure.
2. The history DTC will clear after 50 fault-free ignition cycles.
3. Use the scan tool in order to clear the DTCs.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, observe STEERING WHEEL CONTROLS parameter in dash integration module data list. If scan tool indicates STEERING WHEEL CONTROLS parameter is 0-7 counts, problem is intermittent. Check wiring and connections. If scan tool indicates STEERING WHEEL CONTROLS parameter is not 0-7 counts, go to next step.
3. Replace steering wheel controls. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
4. Use scan tool to clear DTCs. Turn ignition on. If DTC B2805 does not reset, system is okay. If DTC B2805 resets, go to step 2 .

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Powertrain Control Module (PCM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The PCM applies a 5 volt reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the A/C refrigerant pressure sensor signal to the PCM to vary. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low. When pressure is high the PCM commands the cooling fans on. When pressure is too high or too low the PCM will not allow the A/C compressor clutch to engage. When the DTC is set, the PCM does not allow the A/C compressor clutch to engage. This is done to protect the compressor.

1. The engine is running.
2. The A/C is requested.

1. The A/C refrigerant pressure sensor signal voltage is less than 0.1 volt.
2. The A/C refrigerant pressure sensor signal voltage is more than 4.95 volts.
3. Either of the above conditions are present for more than 20 seconds.

1. The PCM stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The PCM disables the A/C compressor clutch.
4. The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

1. A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The current DTC will clear when the diagnostic runs and does not fail.
3. The DTC can be cleared with a scan tool.

Note. Be sure to verify that the PCM engine grounds are secure and clean.

If DTC P0530 cannot be duplicated, reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition off. Check A/C compressor for free rotation. Start engine. Place HVAC control module in OFF position. If A/C compressor operates, go to «TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-f-compressor-clutch-does-not) under SYMPTOM TESTS. If A/C compressor does not operate, go to next step.
3. Install scan tool. Turn ignition on. Using scan tool, observe A/C HIGH SIDE PRESSURE parameter in powertrain control module engine data 2 list. If scan tool indicates A/C HIGH SIDE PRESSURE parameter is within .1-4.9 volts, problem is intermittent. Check wiring and connections. If scan tool indicates A/C HIGH SIDE PRESSURE parameter is not within .1-4.9 volts, go to next step.
4. Turn ignition off. Disconnect A/C refrigerant pressure sensor. Turn ignition on. Using scan tool, observe A/C HIGH SIDE PRESSURE parameter. If scan tool indicates A/C HIGH SIDE PRESSURE parameter is less than .1 volt, go to next step. If scan tool indicates A/C HIGH SIDE PRESSURE parameter is greater than .1 volt, go to step 11 .
5. Turn ignition off. Connect 3-amp fused jumper wire between A/C refrigerant pressure sensor connector terminals "B" (Gray wire) and "C" (Red/Black wire). Turn ignition on. Using scan tool, observe A/C HIGH SIDE PRESSURE parameter. If scan tool indicates A/C HIGH SIDE PRESSURE parameter is greater than 4.9 volts, go to next step. If scan tool indicates A/C HIGH SIDE PRESSURE parameter is less than 4.9 volts, go to step 9 .
6. Disconnect fused jumper wire. Measure voltage between A/C refrigerant pressure sensor connector terminals "B" (Gray wire) and "A" (Black wire). If voltage is less than 5 volts, go to next step. If voltage is greater than 5 volts, go to step 8 .
7. Turn ignition off. Disconnect negative battery cable. Measure resistance between A/C refrigerant pressure sensor connector terminal "A" (Black wire) and ground. If resistance is less than 5 ohms, go to step 13 . If resistance is greater than 5 ohms, go to step 12 .
8. Check Gray wire between A/C refrigerant pressure sensor connector terminal "B" and PCM connector C2, terminal No. 34 for short to voltage. Repair Gray wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
9. Check Gray wire between A/C refrigerant pressure sensor connector terminal "B" and PCM connector C2, terminal No. 34 for a short to ground, high resistance, or an open. Repair Gray wire as necessary, then go to step 17 . If circuit is okay, go to next step.
10. Check Red/Black wire between A/C refrigerant pressure sensor connector terminal "C" and PCM connector C2, terminal No. 27 for a short to ground, high resistance, or an open. Repair Red/Black wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
11. Check Red/Black wire between A/C refrigerant pressure sensor connector terminal "C" and PCM connector C2, terminal No. 27 for a short to voltage. Repair Red/Black wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
12. Disconnect PCM. Check Black wire between A/C refrigerant pressure sensor connector terminal "A" and PCM connector C2, terminal No. 35 for high resistance or an open. Repair Black wire as necessary, then go to step 17 . If circuit is okay, go to step 14 .
13. Check A/C refrigerant pressure sensor harness connector for poor connections. Repair as necessary, then go to step 17 . If connections are okay, go to step 15 .
14. Check PCM harness connector for poor connections. Repair as necessary, then go to step 17 . If connections are okay, go to step 16 .
15. Replace A/C refrigerant pressure sensor. See «REFRIGERANT PRESSURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
16. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under «COMPUTERIZED ENGINE CONTROLS»(/buick/lesabre/viii-2000-2005/remont/removal-installation/#how-to-overhaul-installation-the-engine-controls-removal__powertrain-control-module) in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs are complete, go to next step.
17. Use scan tool to clear DTCs. Start engine. Turn HVAC controls on. If DTC P0530 does not reset, system is okay. If DTC P0530 resets, go to step 2 .

DTC P1536: COOLANT OVERPRESSURE DISABLES A/C

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The coolant temperature sensor is a thermistor. The PCM determines the temperature of the engine coolant based on the voltage from the sensor. When the sensor is cold, its resistance and voltage are high. When the sensor is warm, its resistance and voltage are low. The PCM sends the coolant temperature data to the Dash Integration Module (DIM) over the Class 2 serial data circuit. The DIM will not request A/C clutch engagement if the engine coolant temperature is high. If the PCM determines that a fault is present in the coolant temp sensor circuit it will set DTC P0117 or P0118 and use a default coolant temperature value. This value is then sent from the PCM to the DIM over the Class 2 serial data circuit.

The DIM must be powered.

The engine coolant temperature is equal to or greater than 250°F (121°C) for more than 2 seconds.

The DIM disables the A/C clutch.

1. When the engine coolant temperature drops to less than 246°F (119°C) the DIM will clear the current DTC and go to a history DTC. If A/C is still requested, the DIM will then enable the A/C clutch.
2. The history DTC will clear after 40 ignition cycles.
3. Use a scan tool in order to clear the DTC.

If DTC P1536 is stored as a history code it indicates that the DIM did receive a high engine coolant temperature message from the PCM. Interrupting A/C compressor operation can occur as a normal function to protect the engine from overheating, as when pulling a trailer up a hill. If the condition occurs frequently, check the following for a possible cause

1. Inoperative engine cooling fans.
2. Debris in front of the A/C condenser.
3. Radiator or A/C condenser air shields missing or out of location.
4. Low coolant level.
5. Inoperative thermostat.
6. Water pump failure.
7. Test the PCM for current or history engine coolant temperature sensor DTCs.
8. Trailer weight exceeding 1000 lbs (454 kg) in extreme high ambient temperatures.
9. Aftermarket products affecting cooling system performance.
10. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

Check for cooling system problems, including but not limited to such items as inoperative cooling fans, debris in front of A/C condenser, radiator air shields missing or mislocated, low coolant level, inoperative thermostat, and/or defective water pump.

DTC P1540: A/C REFRIGERANT OVERPRESSURE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

The Powertrain Control Module (PCM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The PCM applies a 5 volt reference and a low reference to the sensor. When the pressure is low, the sensors voltage is low. When the pressure is high, the sensors voltage is high. The PCM sends the A/C pressure data to the Dash Integration Module (DIM) over the Class 2 serial data circuit. The DIM will not request A/C compressor clutch engagement if the A/C pressure is too high.

The DIM must be powered.

The A/C refrigerant pressure is greater than 430 psi (2968 kPa) for more than 500 milliseconds.

The DIM disables the A/C clutch.

1. When the A/C refrigerant pressure drops to less than 1386 kPa (201 psi) the DIM will clear the current DTC and go to a history DTC. If A/C is still requested, the DIM will then enable the A/C clutch.
2. The history DTC will clear after 40 ignition cycles.
3. Use a scan tool in order to clear the DTC.

1. If DTC P1540 is stored as a history code it indicates that the DIM did receive a high A/C refrigerant pressure message from the PCM. This code could also be caused by an intermittent short to voltage on the A/C refrigerant pressure sensor signal circuit which would cause the PCM to set DTC P0530. The code could be the result of an actual A/C refrigerant over-pressure condition.
2. It is possible for the refrigerant system pressure to exceed 430 psi (2968 kPa) during extended engine idle speed with A/C on when ambient temperatures are greater than 105°F (41°C). This could be caused by: An overcharged A/C system. A failed A/C refrigerant pressure sensor. Blockage in a refrigerant line. Debris in front of the A/C condenser. Radiator or A/C condenser air shields missing or out of location. Inoperative engine cooling fans. Extended periods at idle in city traffic followed by rapid acceleration. Aftermarket products affecting cooling system performance.
3. If the condition is not present, condition is intermittent. See information on INTERMITTENTS under «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Wait 2 minutes for A/C system pressure to equalize. Using scan tool, observe current DTC list in Dash Integration Module (DIM) data list. If DTC P1540 is stored as current, go to next step. If DTC P1540 is not stored as current, problem is intermittent. Check for cooling system problems, including but not limited to such items as inoperative cooling fans, debris in front of A/C condenser, radiator air shields missing or mislocated and/or overcharged system.
3. Install manifold gauge. Using scan tool, observe A/C PRESSURE parameter in dash integration module A/C information list. If scan tool indicates system pressure is near gauge pressure within - 0 to +0 psi (- 1.4 to +1.4 kg/cm) of each other, go to next step. If scan tool indicates system pressure is not near gauge pressure within - 0 to +0 psi (- 1.4 to +1.4 kg/cm) of each other, perform A/C system performance test. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
4. Replace A/C refrigerant pressure sensor. See «REFRIGERANT PRESSURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
5. Use scan tool to clear DTCs. Turn ignition on. If DTC P1540 does not reset, system is okay. If DTC P1540 resets, go to step 2 .

DTC P1546: A/C COMPRESSOR CLUTCH RELAY

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

Battery positive voltage is supplied to the switch side of the A/C compressor clutch relay and ignition 3 voltage is supplied to the coil side of the A/C compressor clutch relay. The Powertrain Control Module (PCM) controls the relay by grounding the A/C compressor clutch relay control circuit through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be near zero volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.

The PCM will monitor the control circuit for the following

1. A short to ground.
2. A short to voltage.
3. An open circuit.
4. An open relay coil.
5. An internally shorted or excessively low resistance relay coil.

When the PCM detects any of the above malfunctions, this DTC is set and the affected driver is disabled.

1. The ignition voltage is 9.0-18.0 volts.
2. The engine speed is more than 80 RPM.
3. The PCM driver transitions from ON to OFF or from OFF to ON.

1. A short to ground, an open circuit, or a short to battery voltage is detected on the A/C compressor clutch relay control circuit.
2. The condition is present for more than 30 seconds.

1. The PCM will not illuminate the Malfunction Indicator Light (MIL).
2. The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.

1. A History DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using a scan tool.

Note. Be sure to verify that the PCM engine grounds are secure and clean.

If DTC P1546 cannot be duplicated, reviewing the Failure Records vehicle millage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.

If the condition is not present, condition is intermittent. See information on INTERMITTENTS under SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in LESABRE article in MANUAL A/C-HEATER SYSTEMS.

1. Did you perform Diagnostic System Check. If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, command A/C RELAY ON and OFF in special functions, engine output controls list. If A/C compressor clutch relay turns ON and OFF with each command, problem is intermittent. Ensure PCM engine grounds are clean and secure. Check wiring and connections. If A/C compressor clutch relay does not turn ON and OFF with each command, go to next step.
3. Turn ignition off. Disconnect A/C compressor clutch relay. Turn ignition on. Using a test light connected to ground, probe A/C compressor clutch relay connector terminal No. 30. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
4. Connect test light between A/C compressor clutch relay connector terminals No. 30 and 85. Using scan tool, command A/C RELAY ON and OFF. If test light turns on and off with each command, go to step 9 . If test light does not turn on and off with each command, go to next step.
5. If test light remain illuminated with each command, go to step 7 . If test light does not remain illuminated with each command, go to next step.
6. Check Dark Green/White wire between A/C compressor clutch relay connector terminal No. 85 and PCM connector C2, terminal No. 39 for a short to voltage or an open. Repair Dark Green/White wire as necessary, then go to step 13 . If circuit is okay, go to step 10 .
7. Check Dark Green/White wire between A/C compressor clutch relay connector terminal No. 85 and PCM connector C2, terminal No. 39 for a short to ground. Repair Dark Green/White wire as necessary, then go to step 13 . If circuit is okay, go to step 10 .
8. Repair battery positive voltage circuit of A/C compressor clutch relay. After repairs are complete, go to step 13 .
9. Check A/C compressor clutch relay for poor connections. Repair as necessary, then go to step 13 . If connections are okay, go to step 11 .
10. Check PCM harness connector for poor connections. Repair as necessary, then go to step 13 . If connections are okay, go to step 12 .
11. Replace A/C compressor clutch relay located in underhood fuse block. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
12. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under «COMPUTERIZED ENGINE CONTROLS»(/buick/lesabre/viii-2000-2005/remont/removal-installation/#how-to-overhaul-installation-the-engine-controls-removal__powertrain-control-module) in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs are complete, go to next step.
13. Use scan tool to clear DTCs. Start engine and increase engine speed to more than 80 RPM. If DTC P1546 does not reset, system is okay. If DTC P1546 resets, go to step 2 .

A/C PRESSURE ZONE "A" DIAGNOSIS

Note. Tools Required: ACR 2000 Air Conditioning Service Center (J-43600) or equivalent.

1. Were you sent here from the A/C PERFORMANCE TEST? If so, go to next step. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
2. See the air outlet temperatures recorded during the A/C system performance test. Is there a 2-3 degree difference or more in the discharge air temperature between the right and left center I/P outlets? If so, go to step 7. If not, go to next step.
3. Did the customer concern mention that the A/C system output temperatures are good at first, but then turn warm during extended drives? If so, go to next step. If not, go to step 5.
4. Increase engine speed to 2000 RPM. During extended operation of the A/C system, does the low-side pressure decrease (possibly accompanied by heavy frost on the liquid line between the orifice tube and the evaporator)? If so, go to «A/C PRESSURE ZONE "D" DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-pressure-zone-d-diagnosis). If not, go to next step.
5. See the pressures recorded during the A/C performance test. Inspect for the following conditions: The high-side pressure slightly above the specified pressure ranges but still within zone "A" on the A/C Pressure-Zone Classification Chart. (Scheme 8) The discharge line is hot. The suction line is cool. Do the listed conditions exist? If so, go to next step. If not, go to step 7.
6. See the pressures recorded during the A/C system performance test. Inspect for the following conditions: The low-side pressure slightly lower than the specified pressure ranges but still within zone "A" on the A/C Pressure-Zone Classification Chart. (Scheme 8) The discharge line is warm-to-hot. The suction line is cool-to-warm. Do the listed conditions exist? If so, go to step 8. If not, go to TEST J: TOO HOT IN VEHICLE in SYMPTOM TESTS.
7. The A/C system may be undercharged. Leak test A/C system. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Recharge the A/C system to specifications. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After the repairs are complete, go to step 14.
8. The A/C system may be contaminated. View the ACR 2000 Air Conditioning Service Center information screen for detection of foreign gases in the A/C system. Do foreign gases exist? If so, go to next step. If not, go to step 10.
9. Evacuate the A/C system to a scavenging tank. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Recharge the A/C system to specifications. After repairs are complete, go to step 14.
10. The A/C system may contain too much moisture or air. Evacuate and recharge the A/C system to specifications. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Operate the A/C system and check the outlet air temperatures. (Scheme 7) Are the outlet temperatures within the specified ranges of the Table? If so, go to step 15. If not, go to next step.
11. The A/C system may contain too much refrigerant oil. Recover the refrigerant from the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Remove the accumulator. See «ACCUMULATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Drain and measure the refrigerant oil from the accumulator. Was there more than 5 ozs. (148 ml) of refrigerant oil drained from the accumulator? If so, go to next step. If not, go to step 13.
12. Reinstall the accumulator. Flush the A/C system. See FLUSHING PROCEDURES in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. See ACCUMULATOR under REMOVAL & INSTALLATION. Add the specified amount of refrigerant oil to the accumulator. See SPECIFICATIONS. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step 14.
13. Add the specified amount of refrigerant oil to the accumulator. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__specifications). Install the accumulator. See «ACCUMULATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to next step.
14. Record the low and high-side pressures and the I/P outlet air temperature. Compare the outlet temperatures to those listed in the table? (Scheme 7) Are the high and low-side pressures and outlet temperatures within specifications? If so, go to next step. If not, go to step «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
15. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system okay. If not, go to «TROUBLESHOOTING»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__trouble-shooting).

Scheme 8

A/C PRESSURE ZONE "B" DIAGNOSIS

Note. Tools Required: ACR 2000 Air Conditioning Service Center (J-43600) or equivalent.

1. Were you sent here from the A/C PERFORMANCE TEST? If so, go to next step. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
2. After continued operation of the A/C system, do the low and high-side pressures equalize or become static? If so, go to step 5. If not, go to next step.
3. See the pressures recorded during the A/C PERFORMANCE TEST. Inspect for the following conditions: The low-side pressure equal to or above the specified pressure range of the A/C Performance Table. (Scheme 7) The high-side pressure is below the specified pressure range of the A/C Performance Table. (Scheme 7) The low-side refrigerant line at the compressor feels cool-to-warm. The high-side refrigerant line at the compressor feels warm-to-hot. Do the listed conditions exist? If so, go to step 5. If not, go to next step.
4. See the pressures recorded during the A/C PERFORMANCE TEST. Inspect for the following conditions: The low-side pressure is above the specified pressure range of the A/C Performance Table. (Scheme 7) The high-side pressure is below the specified pressure range of the A/C Performance Table. (Scheme 7) The low-side refrigerant line at the compressor feels warm. The high-side refrigerant line at the compressor feels warm to hot. Do the listed conditions exist? If so, go to next step. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
5. The A/C system has a low refrigerant charge. Evacuate and recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to next step.
6. After you perform the repairs, record the low and the high-side pressures and the I/P outlet air temperature Compare the pressures and the temperature to those listed in the table. (Scheme 7) Are the readings within the specified ranges found on the table? If so, go to step 13. If not, go to next step.
7. The A/C compressor is malfunctioning. Remove the orifice tube and inspect for contamination. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Are there metal flakes on the orifice tube? If so, go to step 9. If not, go to next step.
8. Inspect the orifice tube for a Brown, powdery residue indicating desiccant in the A/C system. Is there a Brown, powdery residue present? If so, go to step 11. If not, go to step 12.
9. Remove the compressor hose from the compressor. See «COMPRESSOR HOSE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Inspect for metal flake contamination at the line connections and the compressor ports. Is there metal flake contamination present? If so, go to next step. If not, go to step 12.
10. Replace the A/C compressor. See «COMPRESSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__compressor) under REMOVAL & INSTALLATION. Replace the orifice tube. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step 13.
11. Flush the A/C system. See FLUSHING PROCEDURES in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Replace the orifice tube. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Replace the A/C compressor. See «COMPRESSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__compressor) under REMOVAL & INSTALLATION. Replace the accumulator. See «ACCUMULATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step 13.
12. Replace the A/C compressor. See «COMPRESSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__compressor) under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to next step.
13. Operate the system in order to verify the repair Did you find and correct the condition? If so, system is okay. If not, see SYMPTOM DIAGNOSIS under «TROUBLESHOOTING»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__trouble-shooting).

A/C PRESSURE ZONE "C" DIAGNOSIS

Note. Tools Required: ACR 2000 Air Conditioning Service Center (J-43600) or equivalent.

1. Were you sent here from the A/C PERFORMANCE TEST? If so, go to step 2. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
2. With the engine idling, turn on the A/C. Inspect for proper cooling fan operation. Are the cooling fans on and operating properly? If so, go to next step. If not, go to step 5.
3. Visually inspect for restricted air flow, damaged condenser cooling fins and inspect for missing or misaligned air baffles. Do the listed conditions exist? If so, go to next step. If not, go to step 6.
4. Repair the air flow restriction. After repairs are complete, go to step 9.
5. Repair the cooling fan operation fault. See appropriate ELECTRIC COOLING FANS article in ENGINE COOLING. After repairs are complete, go to step 9.
6. Feel the liquid line on both sides of the orifice tube. Is the temperature the same before and after the orifice tube? If so, go to next step. If not, go to step 8.
7. Replace the damaged/faulty orifice tube. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 9.
8. Air is in the refrigerant system, or the system is overcharged. See the view screen on the ACR 2000 Air Conditioning Service Center for foreign gas content in the refrigerant. Recover and recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step 9.
9. Record the low and high-side pressures and the I/P outlet air temperature after repairs are performed. Compare the pressures and outlet temperature to those listed in the A/C Performance table. (Scheme 7) Are the readings within the specified ranges? If so, go to next step. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
10. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to SYMPTOM DIAGNOSIS under «TROUBLESHOOTING»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__trouble-shooting).

A/C PRESSURE ZONE "D" DIAGNOSIS

Note. Tools Required: ACR 2000 Air Conditioning Service Center (J-43600) or equivalent.

1. Were you sent here from the A/C PERFORMANCE TEST? If so, go to step 2. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
2. Feel the liquid line before the orifice tube. Is the liquid line cold before the orifice tube? If so, go to next step. If not, go to step 8.
3. Feel along the surfaces of the compressor discharge hose, the condenser and the liquid line between the condenser and the orifice tube. Did you detect an abrupt drop in temperature along the surfaces of any of the listed components? If so, go to step 7. If not, go to next step.
4. Feel the liquid line at the orifice tube location for extreme cold, possibly accompanied by heavy frost. Feel along the liquid line beyond the orifice tube location for warm temperature. Is the liquid line extremely cold at the orifice tube location and warm beyond the orifice tube location? If so, go to step 11. If not, go to next step.
5. Feel along the surfaces of the evaporator inlet tube between the orifice tube and the evaporator core, the evaporator outlet tube between the evaporator core and the compressor, the accumulator and the compressor suction hose. Did you feel an abrupt temperature change along the surfaces of any of the listed components? If so, go to step 7. If not, go to next step.
6. Feel along the surfaces the evaporator inlet tube between the orifice tube and the evaporator core, the evaporator outlet tube between the evaporator core and the accumulator, the accumulator, the compressor suction hose, the compressor discharge hose, the condenser and the evaporator inlet tube between the condenser and the orifice tube. Are the temperatures of these components only mildly warm? If so, go to step 14. If not, go to step 8.
7. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Remove the restriction from the component, or replace the component which produced an abrupt temperature drop. After repairs are complete, go to step 9.
8. Recover the refrigerant and evacuate the system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Record the weight of the recovered refrigerant. Compare the weight of the recovered refrigerant with the total A/C system charge weight. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__specifications). Is the weight of the recovered refrigerant charge greater than 75 percent of the total system capacity? If so, go to next step. If not, go to step 10.
9. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Is the cooling performance improved? If so, go to step 21. If not, go to next step.
10. Leak test the system. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Repair any leaks. After repairs are complete, go to step 21.
11. The orifice tube is restricted. Replace the orifice tube. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Are metal flakes present? If so, go to next step. If not, go to step 13.
12. Remove the compressor hose assembly from the vehicle. See «COMPRESSOR HOSE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Inspect the hose for debris by blowing shop air through one end of the hose while covering the other end with a shop towel. Observe the amount of debris collected in the shop towel. Did a large amount of debris collect in the shop towel? If so, go to step 18. If not, go to step 20.
13. If the orifice tube was restricted with a Brown or Black residue, replace the accumulator. See «ACCUMULATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 21.
14. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the compressor hose from the compressor. See «COMPRESSOR HOSE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Inspect for the presence of debris in the compressor suction port. Is debris present in the compressor suction port? If so, go to next step. If not, go to step 19.
15. Remove the debris from the suction port. Inspect the orifice tube for damage or debris. See ORIFICE TUBE under REMOVAL & INSTALLATION. Did you find evidence of damage or debris? If so, go to step 17. If not, go to next step.
16. If the orifice tube does not show any signs of damage or debris, perform the following procedure: Remove the compressor hose assembly from the vehicle. See «COMPRESSOR HOSE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Inspect the hose for debris by blowing shop air through one end of the hose while covering the other end with a shop towel. Observe the amount of debris collected in the shop towel. Did a large amount of debris collect in the shop towel? If so, go to step 18. If not, go to step 19.
17. Replace the orifice tube. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. If the orifice tube was restricted, observe the type of debris present. Are metal flakes present? If so, go to step 12. If not, go to step 13.
18. If a large amount of debris was collected in the shop towel from the compressor hose assembly, perform the following procedure: Replace the accumulator. See «ACCUMULATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 19.
19. Install the compressor hose assembly. See «COMPRESSOR HOSE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 21.
20. Install the compressor hose assembly. See «COMPRESSOR HOSE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to next step.
21. Record the low and the high-side pressures and the panel outlet air temperature after you perform the repairs. Compare the pressures and the panel outlet temperature to those listed in the A/C Performance table. (Scheme 7) Are the readings within the specified ranges as shown on the A/C Performance table? If so, go to next step. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS.
22. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to SYSTEM DIAGNOSIS under «TROUBLESHOOTING»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__trouble-shooting).

SYMPTOM TESTS

SYMPTOM TEST INDEX

TEST A: AIR DELIVERY IMPROPER

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Turn off all A/C controls. If blower motor is off, go to next step. If blower motor is on, go to «TEST C: BLOWER MOTOR ALWAYS ON»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-c-blower-motor-always-on) .
3. Place blower switch in each speed position. If blower motor operates in any speed position, go to next step. If blower motor does not operate, go to «TEST D: BLOWER MOTOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-d-blower-motor-inoperative) .
4. If blower motor operates in each speed position, go to next step. If blower motor does not operate in each speed position, go to «TEST E: BLOWER MOTOR MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-e-blower-motor-malfunction) .
5. Place blower switch in maximum position. Place mode switch in BI-LEVEL position. Place recirculation switch in ambient position, then RECIRCULATION position. If recirculation door moves when recirculation switch is changed, go to next step. If recirculation door does not move, go to «TEST B: AIR RECIRCULATION MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-b-air-recirculation-malfunction) .
6. Connect scan tool to data link connector at lower left side of instrument panel. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe CURRENT DTC LIST in instrument panel module data list. If any DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If no DTCs are present, go to next step.
7. Place mode switch in each position. If display on A/C control panel responds correctly to mode switch changes, go to next step. If display does not change with switch changes, go to step 14 .
8. Place mode switch and defrost switch in each mode position. Check airflow from outlets. If airflow is sufficient from each outlet in each position, check for loose wires and/or poor connections causing an intermittent. If airflow is not sufficient, go to next step.
9. Using scan tool, observe HTR/DEF/AC DR. COMMANDED parameter in instrument panel module data list. Place mode switch and defrost switch in each mode position. If scan tool indicates HTR/DEF/A/C parameter changes with each switch change, go to next step. If parameter does not change, go to step 15 .
10. Check terminals No. 5 (Brown wire) and No. 7 (Yellow wire) at mode actuator harness connector for high resistance. If high resistance is present, repair wire(s) and go to step 19 . If high resistance is not present, go to next step.
11. Inspect air distribution system for dirty air filter (if equipped), airflow obstruction, air leaks or misaligned ducts. If problem was found and corrected, go to step 19 . If no problems are found, go to next step.
12. Check mode door and mode actuator for misalignment, broken or binding linkages, an obstruction preventing door from reaching full travel, or missing or misaligned door seals. If problem was found and corrected, go to step 19 . If no problems are found, go to next step.
13. Check mode actuator harness connector for poor connections. If problem was found and corrected, go to step 19 . If no problems are found, go to step 16 .
14. Check HVAC control module harness connector for poor connections. If problem was found and corrected, go to step 19 . If no problems are found, go to step 17 .
15. Check Instrument Panel Integration Module (IPM) harness connector for poor connections. If problem was found and corrected, go to step 19 . If no problems are found, go to step 18 .
16. Replace mode actuator. See «MODE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 19 .
17. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 19 .
18. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
19. Start engine. Operate system. If system operates correctly, system is okay. If system does not operate correctly, go to step 2 .

TEST B: AIR RECIRCULATION MALFUNCTION

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Observe the current DTC list in instrument panel module data list. If any DTCs are displayed go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. In no DTCs are displayed, go to next step.
3. Turn ignition on. Place blower motor switch in maximum speed position. Place mode switch in BI-LEVEL position. Alternately place recirculation switch in recirculation and ambient air positions. If recirculation door moves from recirculation position to ambient air position, check wiring for intermittents and poor connections. If door does not move, go to next step.
4. Using scan tool, observe AIR INLET DR COMMANDED parameter in instrument panel module data list. Alternately place recirculation switch in recirculation and ambient air positions. If scan tool indicates that AIR INLET DOOR COMMANDED parameter changes for each change in selected position, go to step 6 . If scan tool does not show parameter changes, go to next step.
5. Using scan tool, command recirculation door from OUTSIDE to RECIRC. Observe AIR INLET DOOR COMMANDED parameter. If scan tool indicates that AIR INLET DOOR COMMANDED parameter changes, go to step 10 . If scan tool does not show parameter changes, go to step 11 .
6. Check ignition 3 voltage circuit and ground circuit of the recirculation actuator for high resistance. If high resistance is found, correct condition and go to step 15 . If high resistance is not found, go to next step.
7. Inspect air distribution system dirty HVAC air filter, if applicable, an obstruction to airflow, air leaks or misaligned air ducts. Correct condition and go to step 15 . If system is okay, go to next step.
8. Inspect recirculation door and actuator for misalignment, broken or binding linkages or recirculation door, an obstruction preventing recirculation actuator from operating within its full range of motion, missing or misaligned seals to recirculation door. Correct condition and go to step 15 . If system is okay, go to next step.
9. Inspect the recirculation actuator for poor connections at the harness connector. Correct condition and go to step 15 . If connections are okay, go to step 12 .
10. Inspect the HVAC control module for poor connections at the harness connector. Correct condition and go to step 15 . If connections are okay, go to step 13 .
11. Inspect the Instrument Panel Integration Module (IPM) for poor connections at the harness connector. Correct condition and go to step 15 . If connections are okay, go to step 14 .
12. Replace recirculation actuator. See «RECIRCULATION ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 15 .
13. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 15
14. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
15. Operate system in order to verify the repair. If condition still exists, go to step 2 . If system operates normally, test is complete.

TEST C: BLOWER MOTOR ALWAYS ON

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Connect scan tool to data link connector at lower left side of instrument panel. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe CURRENT DTC LIST in instrument panel module data list. If any DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If no DTCs are present, go to next step.
3. Turn ignition on. Turn off all A/C controls. If blower motor is off, check for loose wires and/or poor connections causing an intermittent. If blower motor is on, go to next step.
4. Using scan tool, observe COMMANDED BLOWER parameter in instrument panel module data list. If scan tool indicates parameter is near zero percent, go to step 6 . If parameter is not near zero percent, go to next step.
5. Using scan tool, command blower motor OFF. Observe COMMANDED BLOWER parameter. If scan tool indicates parameter is near zero percent, go to step 8 . If parameter is not near zero percent, go to step 9 .
6. Disconnect IPM harness connector. If blower motors stops running, go to step 9 . If blower motor continues to run, go to next step.
7. Check blower motor control module harness connector for poor connections. If problem was found and corrected, go to step 13 . If no problem is found, go to step 10 .
8. Check HVAC control module harness connector for poor connections. If problem was found and corrected, go to step 13 . If no problem is found, go to step 11 .
9. Check Instrument Panel Integration (IPM) module harness connector for poor connections. If problem was found and corrected, go to step 13 . If no problem is found, go to 12 .
10. Replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
11. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
12. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
13. Start engine. Operate system. If system operates correctly, system is okay. If system does not operate correctly, go to step 2 .

TEST D: BLOWER MOTOR INOPERATIVE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Connect scan tool to data link connector at lower left side of instrument panel. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe CURRENT DTC LIST in instrument panel module data list. If any DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If no DTCs are present, go to next step.
3. Turn ignition on. Place blower switch in each speed position. If blower motor operates in any speed position, check for loose wires and/or poor connections causing an intermittent. If blower motor does not operate in any speed position, go to next step.
4. Place blower switch in maximum position. Using scan tool, observe COMMANDED BLOWER parameter in instrument panel module data list. If scan tool indicates parameter is near 100 percent, go to step 9 . If parameter is not near 100 percent, go to next step.
5. Using scan tool, command blower motor ON. Observe COMMANDED BLOWER parameter. If parameter is near 100 percent, go to step 14 . If parameter is not near 100 percent, go to step 15 .
6. Turn ignition off. Disconnect blower motor connector. Turn ignition on. Connect test light between blower motor connector terminals "B" (Purple wire) and "A"(Black wire). Place blower switch in minimum position. If test light illuminates, go to step 12 . If test light does not illuminate, go to next step.
7. Check Purple wire between blower motor and blower motor control module for an open, high resistance or short to ground. If problem was found and corrected, go to step 20 . If circuit was okay, go to next step.
8. Check ground circuit (Black wire) at blower motor control module for an open or high resistance. If problem was found and corrected, go to step 20 . If circuit was okay, go to next step.
9. Ensure blower motor control module and IPM connectors are securely connected. Backprobe IPM connector and measure voltage of terminal No. D11 (Gray/Black wire) to ground. Using scan tool, command blower motor OFF and ON. If voltage is near 5 volts with blower off and near 1.5 volts with blower on, go to step 13 . If voltage is not near specified range, go to next step.
10. Turn ignition off. Disconnect IPM module connector. Turn ignition on. Measure voltage between ground and IPM connector terminal D11 (Gray/Black wire). If voltage is near 5 volts, go to step 15 . If voltage is not near 5 volts, go to next step.
11. Check Gray/Black wire between ground and IPM connector for an open, short to voltage or short to ground. If problem was found and corrected, go to step 20 . If circuit is okay, go to step 13 .
12. Check blower motor harness connector for poor connections. If problem was found and corrected, go to step 20 . If connections are okay, go to step 16 .
13. Check blower motor control module harness connector for poor connections. If problem was found and corrected, go to step 20 . If connections are okay, go to step 17 .
14. Check HVAC control module harness connector for poor connections. If problem was found and corrected, go to step 20 . If connections are okay, go to step 18 .
15. Check IPM harness connector for poor connections. If problem was found and corrected, go to step 20 . If connections are okay, go to step 19 .
16. Replace blower motor. See «BLOWER MOTOR (WITHOUT VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) or «BLOWER MOTOR (WITH VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 20 .
17. Replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 20 .
18. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 20 .
19. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
20. Start engine. Operate system. If system operates correctly, system is okay. If system does not operate correctly, go to step 2 .

TEST E: BLOWER MOTOR MALFUNCTION

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Connect scan tool to data link connector at lower left side of instrument panel. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe CURRENT DTC LIST in INSTRUMENT PANEL MODULE data list. If any DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If no DTCs are present, go to next step.
3. Turn ignition on. Place blower switch in each speed position. If blower motor operates in each speed position, check for loose wires and/or poor connections causing an intermittent. If blower motor does not operate in each speed position, go to next step.
4. Using scan tool, observe COMMANDED BLOWER parameter in instrument panel module data list. Move blower switch from minimum to maximum positions. If scan tool indicates parameter increases from 10 to 100 percent when switch is moved, go to next step. If parameter does not increase, go to step 11 .
5. Turn ignition off. Disconnect blower motor. Turn ignition on. Connect test light between blower supply voltage circuit (Purple wire) and control circuit (Black wire) of blower motor. Move blower switch from minimum to maximum positions. If test light illuminates and increases in intensity when switch is moved, go to step 9 . If light intensity does not increase, go to next step.
6. Check for high resistance or an open in blower motor control module battery positive voltage circuit (Orange wire) and ground circuit (Black wire). If problem was found and corrected, go to step 17 . If no problem was found, go to next step.
7. Ensure blower motor control module and IPM connectors are securely connected. Backprobe IPM connector and measure voltage of terminal No. D11 (Gray/Black wire) to ground. Move blower switch from minimum to maximum positions. If voltage decreases from 4.75 to 1.5 volts, go to step 10 . If voltage does not decrease, go to next step.
8. Turn ignition off. Disconnect IPM module connector. Turn ignition on. Measure voltage between ground and IPM connector terminal D11 (Gray/Black wire). If voltage is near 5 volts, go to step 10 . If voltage is not near 5 volts, go to step 12 .
9. Check harness connector of blower motor for poor connections. Repair connections are necessary. Go to step 17 . If connections are okay, go to step 13 .
10. Check harness connector of blower motor control module for poor connections. Repair connections as necessary. Go to step 17 . If connections are okay, go to step 14 .
11. Check HVAC control module harness connector for poor connections. Repair connections as needed. Go to step 17 . If connections are okay, go to step 15 .
12. Check IPM harness connector for poor connections. Repair connections as necessary. Go to step 17 . If connections are okay, go to step 16 .
13. Replace blower motor. See «BLOWER MOTOR (WITHOUT VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) or «BLOWER MOTOR (WITH VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
14. Replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
15. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
16. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
17. Start engine. Operate system. If system operates correctly, system is okay. If system does not operate correctly, go to step 2 .

TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. If any DTCs are present, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If no DTCs are present, go to next step.
3. Start engine. Place blower motor switch in OFF position. Place A/C switch in OFF position. If A/C compressor operates, go to next step. If compressor does not operate, check wiring for intermittents and poor connections and repair as needed.
4. Using scan tool, observe A/C RELAY COMMANDED parameter in powertrain control module engine data list. If scan tool indicates A/C Relay Commanded parameter is ON, go to next step. If commanded parameter is not ON, go to step 8 .
5. Using scan tool, observe CONTROL HEAD parameter in DIM A/C information list. If scan tool displays A/C OFF, go to next step. If scan tool does not display A/C OFF, go to step 13 .
6. Using scan tool, observe A/C REQUESTED parameter in IPM HVAC system data list. If scan tool displays YES, go to next step. If scan tool does not display YES, go to step 14 .
7. Using scan tool, observe A/C CLUTCH DESIRED parameter in DIM A/C information list. If scan tool displays OFF, go to step 16 . If scan tool does not display OFF, go to step 15 .
8. Turn ignition off. Disconnect A/C relay. Turn ignition on. If A/C clutch disengages, go to step 12 . If A/C clutch does not disengage, go to step 10 .
9. Test A/C compressor clutch relay control circuit of A/C compressor clutch relay for a short to ground. A short to ground on A/C compressor clutch control circuit will set DTC P1546. If condition was found and corrected, go to step 23 . If condition was not found, go to step 12 .
10. Test the A/C compressor clutch supply voltage circuit for a short to voltage. If condition was found and corrected, go to step 23 . If condition was not found, go to next step.
11. Inspect the A/C compressor clutch for poor connections. Repair connections as necessary and go to step 23 . If connections are okay, go to step 18 .
12. Inspect the A/C compressor clutch relay for poor connections. Repair connections as necessary and go to step 23 . If connections are okay, go to step 18 .
13. Inspect the HVAC control module for poor connections. Repair connections as necessary and go to step 23 . If connections are okay, go to step 19 .
14. Inspect the IPM for poor connections. Repair connections as necessary and go to step 23 . If connections are okay, go to step 20 .
15. Inspect the DIM for poor connections. Repair connections as necessary and go to step 23 . If connections are okay, go to step 21 .
16. Inspect the PCM for poor connections. Repair connections as necessary and go to step 23 . If connections are okay, go to step 22 .
17. Replace A/C compressor clutch relay. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) in REMOVAL & INSTALLATION. After repairs are complete, go to step 23 .
18. Replace A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step 23 .
19. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 23 .
20. Replace Instrument Panel Module (IMP). See INSTRUMENT PANEL INTEGRATION MODULE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 23 .
21. Replace Dash Integration Module (DIM). See INSTRUMENT PANEL INTEGRATION MODULE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 23 .
22. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under «COMPUTERIZED ENGINE CONTROLS»(/buick/lesabre/viii-2000-2005/remont/removal-installation/#how-to-overhaul-installation-the-engine-controls-removal__powertrain-control-module) in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs are complete, go to step 23 .
23. Start engine. Operate system. If system still does not operate properly, go to step 2 . If system operates properly, test is complete.

TEST G: COMPRESSOR CLUTCH DOES NOT ENGAGE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Connect scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. If any DTCs are displayed, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table in SELF-DIAGNOSTICS. If no DTCs are displayed, go to next step.
3. Start engine. Place blower motor switch in maximum speed position. Place mode switch in DEFROST position. Place air temperature switch in coldest position. If A/C compressor operates, check wiring for intermittents and poor connections. If compressor does not operate, go to next step.
4. Park vehicle out of direct sunlight. Open windows to ventilate interior of vehicle. Allow A/C system to equalize for approximately 2 minutes. Turn ignition off. Install manifold gauge set. Record ambient air temperature at vehicle. Record readings of low and high side static pressures. Compare low and high side pressure values with allowable limits for the recorded ambient air temperature. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS. If low and high side pressure values are within allowable limits for recorded ambient air temperature, and within 15 psi (1.1 kg/cm) of each other, go to next step. If low and high side pressure values are within allowable limits for recorded ambient air temperature, and/or are not within 15 psi (1.1 kg/cm) of each other, leak test vehicle. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
5. Turn ignition on. Using scan tool, observe A/C HIGH SIDE PRESSURE SENSOR parameter in PCM engine data 2 list. Compare A/C high side pressure on scan tool to value on manifold gauge. If low and high side pressure values are within 15 psi (1.1 kg/cm) of each other, go to next step. If low and high side pressure values are not within 15 psi (1.1 kg/cm) of each other, go to step 25 .
6. If HVAC control module is inoperative, go to step 20 . If HVAC control module is operative, go to next step.
7. Start engine. Using scan tool, observe A/C RELAY COMMAND parameter in Powertrain data list. Place air temperature switch in coldest position. If scan tool indicates A/C RELAY COMMAND parameter is ON, go to step 14 . If scan tool indicates A/C RELAY COMMAND parameter is OFF, go to next step.
8. Using scan tool, observe A/C CLUTCH (DESIRED) parameter in DIM A/C information list. If scan tool indicates A/C CLUTCH (DESIRED) parameter is ON, go to next step. If scan tool indicates A/C CLUTCH (DESIRED) parameter is OFF, go to step 10 .
9. Using scan tool, observe A/C CLUTCH (ACTUAL) parameter in DIM A/C information list. If scan tool indicates A/C CLUTCH (ACTUAL) parameter is ON, go to step 14 . If scan tool indicates A/C CLUTCH (ACTUAL) parameter is OFF, go to step 35 .
10. Using scan tool, observe CONTROL HEAD (DESIRED) parameter in DIM A/C information list. If scan tool indicates CONTROL HEAD (DESIRED) parameter is ON, go to next step. If scan tool indicates CONTROL HEAD (DESIRED) parameter is OFF, go to step 13 .
11. Using scan tool, observe PRESSURE STATUS parameter in DIM A/C information list. If scan tool indicates PRESSURE STATUS parameter is NORMAL, go to next step. If scan tool does not indicate PRESSURE STATUS parameter is NORMAL, check for loose wires and/or poor connections causing an intermittent.
12. Using scan tool, observe TEMPERATURE STATUS parameter in DIM A/C information list. If scan tool indicates TEMPERATURE STATUS parameter is okay, go to step 32 . If scan tool does not indicate TEMPERATURE STATUS parameter is okay, check for cause of engine overheating.
13. Using scan tool, observe CONTROL HEAD (DESIRED) parameter in DIM A/C information list. Place mode switch in DEFROST position. If scan tool indicates CONTROL HEAD (DESIRED) parameter turns ON and OFF with each command, go to step 31 . If scan tool indicates CONTROL HEAD (DESIRED) parameter does not turn ON and OFF with each command, go to step 34 .
14. Using scan tool, command A/C compressor clutch relay ON and OFF. If A/C compressor clutch turns ON and OFF with each command, go to step 18 . If A/C compressor clutch does not turn ON and OFF with each command, go to next step.
15. Turn ignition off. Disconnect A/C compressor clutch relay. Turn ignition on. Using a test light connected to ground, probe A/C compressor clutch relay terminal No. 86 (wire color not available). If test light illuminates, go to next step. If test light does not illuminate, go to step 28 .
16. Connect a test light between A/C compressor clutch relay terminals No. 85 and 86. Using scan tool, command A/C compressor clutch relay ON and OFF. If test light turns ON and OFF with each command, go to step 30 . If test light does not turn ON and OFF with each command, go to next step.
17. If test light remains illuminated with each command, go to step 23 . If test light does not remain illuminated with each command, go to step 22 .
18. Turn ignition off. Disconnect A/C compressor clutch relay. Using a test light connected to ground, probe A/C compressor clutch relay terminal No. 30. If test light illuminates, go to next step. If test light does not illuminate, go to step 27 .
19. Connect a 10-amp fused jumper wire between A/C compressor clutch relay terminals No. 30 and 87. If A/C compressor clutch engages, go to step 30 . If A/C compressor clutch does not engage, go to step 24 .
20. Check Brown wire between HVAC control module connector terminal A2 and IGN 3 (10-amp) fuse located in rear fuse block for a short to ground, high resistance or an open. If problem was found and corrected, go to step 43 . If circuit is okay, go to next step.
21. Check HVAC control module connector terminals A1 and A5 for an open in Black wires. If problem was found and corrected, go to step 43 . If circuit is okay, go to step 34 .
22. Check Dark Green/White wire between PCM connector C2, terminal No. 39 and A/C compressor clutch relay terminal No. 85 for an open. If problem was found and corrected, go to step 43 . If circuit is okay, go to step 35 .
23. Check Dark Green/White wire between PCM connector C2, terminal No. 39 and A/C compressor clutch relay terminal No. 85 for a short to ground. If problem was found and corrected, go to step 43 . If circuit is okay, go to step 35 .
24. Check Dark Green wire between A/C compressor clutch connector terminal "A" and A/C compressor clutch relay terminal No. 87 for a short to ground, high resistance or an open. If problem was found and corrected, go to step 43 . If circuit is okay, go to step 26 .
25. Check A/C refrigerant pressure sensor for an open in ground circuit. If problem was found and corrected, go to step 43 . If circuit is okay, go to step 29 .
26. Check Black wire between A/C compressor clutch connector terminal "B" and splice pack SP100 terminal "E" for high resistance or an open. If problem was found and corrected, go to step 43 . If circuit is okay, go to step 33 .
27. Repair switch side battery positive voltage circuit of A/C compressor clutch relay. After repairs are complete, go to step 43 .
28. Repair coil side ignition 3 voltage circuit of A/C compressor clutch relay. After repairs are complete, go to step 43 .
29. Check A/C refrigerant pressure sensor harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 38 .
30. Check A/C compressor clutch relay harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 39 .
31. Check IPM harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 36 .
32. Check DIM harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 37 .
33. Check A/C compressor clutch harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 40 .
34. Check HVAC control module harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 41 .
35. Check PCM harness connector for poor connections. If problem was found and corrected, go to step 43 . If connections are okay, go to step 42 .
36. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 43 .
37. Replace DIM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 43 .
38. Replace A/C refrigerant pressure sensor. See «REFRIGERANT PRESSURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 43 .
39. Replace A/C compressor clutch relay. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 43 .
40. Replace A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step 43 .
41. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 43 .
42. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under «COMPUTERIZED ENGINE CONTROLS»(/buick/lesabre/viii-2000-2005/remont/removal-installation/#how-to-overhaul-installation-the-engine-controls-removal__powertrain-control-module) in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs are complete, go to next step.
43. Operate system. If system operates properly, system is okay. If system does not operate properly, go to step 2 .

TEST H: CONTROL HEAD ILLUMINATION/DISPLAY DOES NOT OPERATE PROPERLY

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe current DTC list in INSTRUMENT PANEL MODULE. If scan tool displays any DTCs, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. When performing Diagnostic System Check, if DTC B2646 displayed for Instrument Panel Module, see DTC B2646: AMBIENT LIGHT SENSOR CIRCUIT RANGE under DIAGNOSTIC TESTS in appropriate HEADLIGHTS AUTOMATIC TWILIGHT SENTINEL article in ACCESSORIES & EQUIPMENT. If DTC B2646 did not display, go to next step.
4. Install scan tool. Turn ignition on. Using scan tool, perform DISPLAY TEST command in instrument panel module special functions. If HVAC control module segments illuminate, go to next step. If all HVAC control module segments do not illuminate, go to step 8 .
5. When performing DISPLAY TEST INSTRUMENT PANEL MODULE command, if all other Vacuum Fluorescent (VF) displays illuminate, go to next step. If all other VF displays do not illuminate, diagnose and repair lighting system problem.
6. Cover sunload sensor assembly. Turn lights on. If backlighting is present, go to next step. If backlighting is not present, diagnose and repair lighting system problem.
7. Adjust dimming control from minimum intensity to maximum intensity. If VF display decreases and increases in intensity, problem is intermittent. Check wiring and connections. If VF display does not decrease and increase in intensity, go to next step.
8. Inspect harness connector of HVAC control module for poor connections. Repair as necessary, then go to step 10 . If connections are okay, go to next step.
9. Replace HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
10. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2 .

TEST I: DEFROSTING INSUFFICIENT

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Check engine temperature. If engine reaches normal operating temperature, go to next step. If engine does not reach normal temperature, go to step 4 .
3. Select minimum blower speed. Select maximum temperature setting. Feel temperature of inlet and outlet hoses at heater core. If inlet hose feels warmer than outlet hose, go to step 5 . If inlet hose is not warmer than outlet hose, go to step 11 .
4. Repair engine for overheating concern. After repairs are complete, go to step 13 .
5. Check A/C compressor clutch operation. If compressor clutch operates, go to step 7 . If compressor clutch does not operate, go to next step.
6. Repair A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step 13 .
7. Perform the A/C system performance test. See «A/C SYSTEM PERFORMANCE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS. If system operates within specifications, go to next step. If system is not within specifications, go to step 10 .
8. Inspect for correct operation of recirculation door. If recirculation door operates correctly, go to step 13 . If door does not operate correctly, go to step 12 .
9. Repair air delivery concern. See «TEST A: AIR DELIVERY IMPROPER»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-a-air-delivery-improper) . After repairs are complete, go to step 13 .
10. Repair the A/C performance concern. See «SYMPTOM TEST INDEX»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table. After repairs are complete, go to step 13 .
11. Repair heating concern. After repairs are complete, go to step 13 .
12. Repair recirculation door concern. See «TEST B: AIR RECIRCULATION MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-b-air-recirculation-malfunction) . After repairs are complete, go to next step.
13. Start engine. Operate system. If system still does not operate properly, go to step 2 . If system operates properly, test is complete.

TEST J: OUTSIDE AIR TEMPERATURE DISPLAY INACCURATE OR INOPERATIVE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Inspect ambient air temperature sensor for obstructions or improper mounting. Repair as necessary, then go to step 8 . If sensor is okay, go to next step.
3. Using scan tool, inspect for current or history codes relating to ECT in PCM. If ECT related DTC are found, see appropriate SELF-DIAGNOSTICS article in ENGINES. Repair as necessary, then go to step 8 . If ECT related DTCS are not found, go to next step.
4. Using scan tool, inspect for current or history codes relating to VSS in PCM. If VSS related DTC are found, see appropriate SELF-DIAGNOSTICS article in ENGINES. Repair as necessary, then go to step 8 . If VSS related DTCS are not found, go to next step.
5. Inspect harness connector of ambient air temperature sensor for poor connections. Repair as necessary, then go to step 8 . If connections are okay, go to next step.
6. Test ambient air temperature sensor resistance. See AMBIENT AIR TEMPERATURE SENSOR under COMPONENT TESTS. If resistance measures near specifications, system is okay. If resistance does not measure near specifications, go to next step.
7. Replace ambient air temperature sensor. See «AIR TEMPERATURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
8. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2 .

TEST K: PASSENGER CONTROL DOES NOT OPERATE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module (IPM) special functions. Observe current DTC list in INSTRUMENT PANEL MODULE data list. If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. Turn ignition on. Using scan tool, observe AUTO HVAC W DUAL ZONE option parameter in DIM special functions set options data list. If scan tool indicates AUTO HVAC W DUAL ZONE option is active, go to next step. If scan tool does not indicate AUTO HVAC W DUAL ZONE option is active, go to step 9 .
4. Turn A/C-heater control panel to AUTO. Using scan tool, observe PASS HVAC SWITCH parameter in driver door module data list. Press warmer (Red) switch, then cooler (Blue) switch on passenger temperature control. If scan tool indicates PASS HVAC SWITCH parameters are within 127-158 counts (Red switch), 51-81 counts (Blue switch) or 04-234 counts (no switch pressed), go to next step. If parameters are not within specification, go to step 16 .
5. Using scan tool, observe RIGHT PROGRAM NUMBER parameter in instrument panel module HVAC system data list. Press warmer (Red) switch, then cooler (Blue) switch on passenger temperature control. If RIGHT PROGRAM NUMBER parameter increases when warmer button is pressed and decreases when cooler button is pressed, go to next step. If RIGHT PROGRAM NUMBER parameter does not increase when warmer button is pressed and does not decrease when cooler button is pressed, go to step 18 .
6. Adjust passenger temperature control from full WARM to full COOL. If any Red or Blue indicators illuminate, go to next step. If any Red or Blue indicators do not illuminate, go to step 11 .
7. Adjust passenger temperature control from full WARM to full COOL. If an indicator illuminates for each temperature adjustment except for neutral, go to step 8 . If an indicator does not illuminate for each temperature adjustment except for neutral, go to step 10 .
8. Adjust passenger temperature control to full WARM. Press OFF one time on A/C control. If all passenger HVAC control indicators turn off, system is okay. If all passenger HVAC control indicators do not turn off, go to step 18 .
9. Using scan tool, enable AUTO HVAC W DUAL ZONE option in DIM set options data list. Go to step 22 .
10. Turn ignition off. Disconnect right air temperature switch assembly. Measure voltage between the battery positive voltage circuit of right air temperature switch assembly and ground. If voltage measures near 12 volts, go to step 12 . If voltage does not measure near 12 volts, go to step 14 .
11. Turn ignition off. Disconnect right air temperature switch assembly. Disconnect Front Passenger Door Module (FPDM). Check FPDM low side input circuits of right air temperature switch assembly for a short to voltage, short to ground or an open circuit. Repair wiring as necessary, then go to step 22 . If wiring is okay, go to step 13 .
12. Measure voltage between battery positive voltage circuit (Orange wire) and ground circuit (Black/White wire) of right air temperature switch assembly. If voltage measures near 12 volts, go to next step. If voltage does not measure near 12 volts, go to step 15 .
13. Connect FPDM. Connect right air temperature switch assembly. Turn ignition on. Turn HVAC control to AUTO. Backprobe FPDM low side input circuits of right air temperature switch assembly with a voltmeter connected to ground. Adjust passenger temperature control from full WARM to full COOL. If voltage goes to zero for at least one switch position for each circuit tested, go to step 16 . If voltage does not go to zero, go to step 17 .
14. Check battery positive voltage circuit (Orange wire) of right air temperature switch assembly for an open circuit. Repair wiring as necessary, then go to step 22 .
15. Check ground circuit (Black/White wire) of right air temperature switch assembly for an open circuit. Repair wiring as necessary, then go to step 22 .
16. Check harness connectors of right air temperature switch assembly and FPDM for poor connections. Repair wiring as necessary, then go to step 22 . If wiring is okay, go to step 19 .
17. Check harness connectors of right air temperature switch assembly and FPDM for poor connections. Repair wiring as necessary, then go to step 22 . If wiring is okay, go to step 20 .
18. Check harness connector of IPM for poor connections. Repair wiring as necessary, then go to step 22 . If wiring is okay, go to step 21 .
19. Replace right air temperature switch assembly. See RIGHT AIR TEMPERATURE SWITCH ASSEMBLY under REMOVAL & INSTALLATION. After repairs are complete, go to step 22 .
20. Replace FPDM. See FRONT PASSENGER DOOR MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 22 .
21. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
22. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2 .

TEST L: STEERING WHEEL CONTROLS INOPERATIVE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe CURRENT DTC list in instrument panel module data list. If scan tool displays any DTCs, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. Install scan tool. Turn ignition on. Using scan tool, observe STEERING WHEEL CONTROLS parameter in dash integration module data list. Press each radio and temperature switch in both directions. If counts change for any switch pressed, go to next step. If counts do not change for any switch pressed, go to step 6 .
4. Using scan tool, observe STEERING WHEEL CONTROLS parameter in dash integration module data list. Press each radio and temperature switch in both directions. If counts change for all switches pressed, go to next step. If counts do not change for all switches pressed, go to step 10 .
5. Turn radio on. Increase and decrease volume with right steering wheel controls switch. If radio steering wheel controls function, see «TEST O: TOO COOL IN CAR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-o-too-cold-in-vehicle) or «TEST P: TOO WARM IN CAR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-p-too-hot-in-vehicle) . If radio steering wheel controls do not function, go to step 11 .
6. Disable SIR system. Turn ignition off. Remove and disconnect right steering wheel controls. Turn ignition on. Connect a 3-amp fused jumper wire between right steering wheel controls connector terminals No. 1 (Purple wire) and No. 6 (Dark Blue wire). If counts change, go to step 10 . If counts do not change, go to next step.
7. Measure voltage of Purple wire at right steering wheel controls connector terminal No. 1 to ground. If voltage measures near 12 volts, go to next step. If voltage does not measure near 12 volts, go to step 9 .
8. Check Dark Blue wire between right steering wheel controls connector terminal No. 6 and Dash Integration Module (DIM) connector C2, terminal A1 for an open or high resistance. Repair Dark Blue wire as necessary, then go to step 14 . If circuit is okay, go to step 11 .
9. Check Purple wire between right steering wheel controls connector terminal No. 1 and DIM connector C3 terminal B3 for an open or short to ground. Repair Purple wire as necessary, then go to step 14 . If circuit is okay, go to step 11 .
10. Inspect harness connector of right steering wheel controls for poor connections. Repair as necessary, then go to step 14 . If connections are okay, go to step 12 .
11. Inspect harness connector of DIM for poor connections. Repair as necessary, then go to step 14 . If connections are okay, go to step 13 .
12. Replace right steering wheel controls. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 14 .
13. Replace DIM. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
14. Enable SIR system. Once SIR system is enabled, go to next step.
15. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2 .

TEST M: SYSTEM DOES NOT MAINTAIN SET TEMPERATURE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe current DTC list in IPM data list. If scan tool displays any DTCS, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. Inspect for a poor battery condition. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. Repair as necessary, then go to step 22. If battery is okay, go to next step.
4. Visually inspect HVAC control module, steering wheel controls and personalization controls for stuck or intermittent sticking switches. Repair as necessary, then go to step 22. If switches are okay, go to next step.
5. Ensure customer is using correct key to enable personalization and is not inadvertently activating steering wheel controls or right air temperature switch assembly. If correct key is being used, go to next step.
6. Install scan tool. Cover sunload sensor assembly. Start engine. Place temperature switch to 75°F (24°C) position. Place right air temperature switch assembly to neutral. Using scan tool, observe RIGHT and LEFT SOLAR SENSOR data parameters in IPM open/short data list. If scan tool indicates both right and left solar sensor parameters are greater than 224 counts, go to next step. If scan tool indicates both right and left solar sensor parameters are less than 224 counts, go to step 17.
7. Uncover sunload sensor assembly. Direct a light source at right and left sides of sunload sensor. If counts change similarly and correspond to proper side of sunload sensor, go to next step. If counts do not change, go to step 17.
8. Fully open all panel outlets. Place temperature switch to 75°F (24°C) position. Place mode switch in PANEL position. Set blower speed to illuminate 2 bars on blower speed display. Place right air temperature switch assembly to neutral. Check for airflow through inside air temperature sensor by placing a 2" square piece of paper over sensor air inlet. If paper stays in place, go to next step. If paper does not stay in place, go to step 16.
9. Turn ignition off. Check right and left panel and heater temperature sensors for correct installation. Repair installation as necessary, then go to step 22. If installation is correct, go to next step.
10. Check fright and left panel and heater temperature sensor harness connectors or poor connections. Repair connections as necessary, then go to step 22. If connections are okay, go to next step.
11. Check temperature sensor resistances. If resistances are to specification, go to next step. If resistances are not to specification, go to step 21.
12. Check ambient air temperature sensor for poor connections. Repair as necessary, then go to step 22. If connections are okay, go to next step.
13. Check ambient air temperature sensor resistance. (Scheme 9) If resistances are to specification, go to next step. If resistances are not to specification, go to step 19.
14. Check inside air temperature sensor for poor connections. Repair as necessary, then go to step 22. If connections are okay, go to next step.
15. Check inside air temperature sensor resistance. (Scheme 9) If resistances are to specification, system is okay. If resistances are not to specification, go to step 20.
16. Check for a blocked or disconnected aspiration hose. Repair as necessary, then go to step 22.
17. Check for correct orientation and poor connection at sunload sensor assembly. Repair as necessary, then go to step 22. If sunload sensor is okay, go to next step.
18. Replace sunload sensor assembly. See «SUNLOAD SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 22.
19. Replace ambient air temperature sensor. See «AIR TEMPERATURE SENSORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 22.
20. Replace inside air temperature sensor. See «AIR TEMPERATURE SENSORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 22.
21. Replace suspect air temperature sensor. See «AIR TEMPERATURE SENSORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
22. Start engine. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2.

TEST N: TEMPERATURE VARIATION BETWEEN DRIVER & PASSENGER OUTLETS

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Observe current DTC list. If scan tool displays any DTCs, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. If customer concern occurred during A/C mode operation, go to next step. If concern did not occur during A/C mode operation, go to step 10 .
4. Ensure outside air temperature is greater than 38°F (3°C). Cover sunload sensor assembly. Start engine. Fully open all panel outlets. Place temperature switch in coldest position. Place mode switch in panel position. Place blower motor switch in maximum speed position. Place right air temperature switch assembly in neutral position. Ensure VENT mode indicator is not illuminated. If difference between right and left center panel outlet temperatures is greater than 10°F (6°C), go to next step. If difference between right and left center panel outlet temperatures is less than 10°F (6°C), system is okay.
5. Perform A/C System Performance test. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS. If low and high side pressures are within specification, go to next step. If pressures are not within specification, repair A/C system as necessary. After repair are complete, go to step 20 .
6. Check right and left panel temperature sensors for correct installation. Repair as necessary, then go to step 20 . If sensors are okay, go to next step.
7. Install scan tool. Cover sunload sensor assembly. Start engine. Adjust temperature switch to 75°F (24°C). Adjust right air temperature switch assembly to neutral. Using scan tool, observe RIGHT and LEFT SOLAR SENSOR data parameters in instrument panel module open/short data list. If scan tool indicates both right and left solar sensor parameters are greater than 224 counts, go to next step. If parameters are not greater than 224 counts, go to step 15 .
8. Uncover sunload sensor assembly. Direct a light source at right and left side of sunload sensor assembly. If counts change similarly and correspond to proper side of sunload sensor, go to next step. If counts do not change, go to step 15 .
9. Install thermometer in panel duct near right and left panel temperature sensors. Using scan tool, observe RIGHT and LEFT A/C DUCT TEMP data parameters and RIGHT and LEFT HTR DUCT TEMP in instrument panel module HVAC sensors data list. If scan tool indicates sensor temperatures near thermometer temperatures are within specified range of 5°F to -5°F (3°C to -3°C), system is okay. If temperatures are not within specified range, go to step 13 .
10. Cover sunload sensor assembly. Start engine. Fully open all panel outlets. Adjust temperature switch to warmest position. Place mode switch in FLOOR (lower) position. Place blower motor switch in maximum speed position. Place right air temperature switch assembly in neutral position. If difference between right and left outlet temperatures are less than 10°F (6°C), system is okay. If difference between right and left outlet temperatures are greater than 10°F (6°C), go to next step.
11. Ensure engine temperature is cool. Check coolant level in radiator and reservoir. If cooling system is okay, go to next step. If cooling system is not okay, repair system as necessary, then go to step 20 .
12. Perform Heating Performance Diagnostic. See «HEATER PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__heater-performance-test) under PERFORMANCE TESTS. If system operates properly, go to step 20 . If system does not operate properly, go to next step.
13. Check harness connector of suspect air temperature sensor for poor connections. Repair as necessary, then go to step 20 . If connections are okay, go to next step.
14. Test suspect air temperature sensor resistance. If sensor resistance is within specifications, go to step 16 . If sensor resistance is not within specification, go to step 18 .
15. Check harness connector of sunload sensor assembly for poor connections. Repair as necessary, then go to step 20 . If connections are okay, go to step 17 .
16. Check for harness connector of IPM poor connections. Repair as necessary, then go to step 20 . If connections are okay, go to step 19 .
17. Replace sunload sensor assembly. After repairs are complete, go to step 20 .
18. Replace suspect air temperature sensor. See «AIR TEMPERATURE SENSORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 20 .
19. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
20. Operate system to verify repair. If system operate properly, system is okay. If system does not operate properly, go to step 2 .

TEST O: TOO COLD IN VEHICLE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe current DTC list in IPM. If scan tool displays any DTCs, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. Place blower motor switch in each speed position. If blower motor operates in any speed position, go to next step. If blower motor does not operate in any speed position, go to «TEST D: BLOWER MOTOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-d-blower-motor-inoperative) .
4. If blower motor operates in each speed position, go to next step. If blower motor does not operate in each speed position, go to «TEST E: BLOWER MOTOR MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-e-blower-motor-malfunction) .
5. If concern occurs when heater or defroster is on, go to next step. If concern does not occur when heater or defroster is on, go to step 9 .
6. Start engine. Turn HVAC controls off. If A/C compressor operates, go to «TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-f-compressor-clutch-does-not) . If A/C compressor does not operate, go to next step.
7. Inspect cooling system for low coolant level, loose or worn accessory drive belt, leaking/kinked radiator hose or heater hose, missing radiator cap pressure seal or leaking radiator cap. Repair as necessary, then go to step 24 . If components are okay, go to next step.
8. Perform Heating Performance Diagnostic. See «HEATER PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__heater-performance-test) under PERFORMANCE TESTS. If heater performs to specification, go to step 24 . If heater does not perform to specification, go to next step.
9. Inspect air temperature sensors for proper installation. Repair as necessary, then go to step 24 . If sensors are installed properly, go to next step.
10. Start engine. Fully open all panel outlets. Place temperature switch in 75°F (24°C) position. Place mode switch in PANEL position. Set blower speed to illuminate 2 bars on fan speed indicator. Place right air temperature switch assembly in neutral position. Inspect for airflow through inside air temperature sensor by placing a 2" square piece of paper over sensor air inlet. If paper stays in place, go to next step. If paper does not stay in place, go to step 15 .
11. Turn ignition on. Install scan tool. Cover sunload sensor assembly. Start engine. Place temperature switch in 75°F (24°C) position. Place right air temperature switch assembly in neutral position. Using scan tool, observe RIGHT and LEFT SOLAR SENSOR data parameters in IPM open/short data list. If scan tool indicates that RIGHT and LEFT SOLAR SENSOR data parameters are greater than 224 counts, go to next step. If scan tool indicates RIGHT and LEFT SOLAR SENSOR data parameters are less than 224 counts, go to step 19 .
12. Uncover sunload sensor assembly. Direct a light source at right and then left side of sunload sensor assembly. If counts change similarly and correspond to proper side of sunload sensor assembly, go to next step. If counts do not change similarly and/or do not correspond to proper side of sunload sensor assembly, go to step 19 .
13. Install a thermometer near air temperature sensors. Using scan tool, observe RIGHT AC DUCT TEMP, RIGHT HTR. DUCT TEMP, LEFT AC DUCT TEMP, LEFT HTR. DUCT TEMP, INSIDE AIR TEMP data parameters in IPM HVAC sensor data list. If scan tool indicate sensor temperatures are near thermometer temperatures within -5 to +5°F (-3 to +3°C), go to next step. If scan tool indicate sensor temperatures are not near thermometer temperatures within -5 to +5°F (-3 to +3°C), go to step 16 .
14. If customer needs to change set temperature frequently to maintain comfort, go to «TEST M: SYSTEM DOES NOT MAINTAIN SET TEMPERATURE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-m-system-does-not-maintain) . If customer does not need to change set temperature frequently to maintain comfort, go to step 18 .
15. Check for a blocked or disconnected aspiration hose. Repair as necessary, then go to step 24 .
16. Inspect for poor connections at harness connector of suspect temperature sensor. Repair as necessary, then go to step 24 . If connections are okay, go to next step.
17. Test suspect temperature sensor resistance. If resistance measures near specification, go to step 20 . If resistance does not measure near specification, go to step 21 .
18. Install scan tool. Turn ignition on. Using scan tool, adjust TEMPERATURE OFFSET in IPM special function/set options as needed. After adjustment, go to step 24 .
19. Inspect harness connector of sunload sensor assembly for poor connections. Repair as necessary, then go to step 24 . If connections are okay, go to step 22 .
20. Inspect harness connector of IPM for poor connections. Repair as necessary, then go to step 24 . If connections are okay, go to step 23 .
21. Replace suspect temperature sensor. See «AIR TEMPERATURE SENSORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 24 .
22. Replace sunload sensor assembly. After repairs are complete, go to step 24 .
23. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
24. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2 .

TEST P: TOO HOT IN VEHICLE

Note. For circuit reference, see CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS .

1. Did you perform the Diagnostic System Check? If so, go to next step. If not, see «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Install scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in instrument panel module special functions. Using scan tool, observe current DTC list in IPM. If scan tool displays any DTCs, go to «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) table under SELF-DIAGNOSTIC SYSTEM. If scan tool does not display any DTCs, go to next step.
3. Place blower motor switch in each speed position. If blower motor operates in any speed position, go to next step. If blower motor does not operate in any speed position, go to «TEST D: BLOWER MOTOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-d-blower-motor-inoperative).
4. If blower motor operates in each speed position, go to next step. If blower motor does not operate in each speed position, go to «TEST E: BLOWER MOTOR MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-e-blower-motor-malfunction).
5. Cover sunload sensor assembly. Start engine. Fully open all panel outlets. Place temperature switch in coldest position. Place mode switch in PANEL position. Place blower motor switch in maximum speed position. Ensure vent, ambient air, indicator is not illuminated. If A/C compressor operates, go to next step. If A/C compressor does not operate, go to «TEST G: COMPRESSOR CLUTCH DOES NOT ENGAGE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-g-compressor-clutch-does-not).
6. Perform A/C SYSTEM PERFORMANCE TEST. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__ac-performance-test) under PERFORMANCE TESTS. If A/C system performs to specifications, go to step 22. If A/C system does not perform to specifications, go to next step.
7. Inspect temperature sensors for proper installation. Repair as necessary, then go to step 22. If sensors are properly installed, go to next step.
8. Start engine. Fully open all panel outlets. Place temperature switch in 75°F (24°C) position. Place mode switch in PANEL (upper) position. Set blower speed to illuminate 2 bars on fan speed indicator. Place right air temperature switch assembly in neutral position. Inspect for airflow through inside air temperature sensor by placing a 2" square piece of paper over sensor air inlet. If paper stays in place, go to next step. If paper does not stay in place, go to step 13.
9. Turn ignition on. Install scan tool. Cover sunload sensor assembly. Start engine. Place temperature switch in 75°F (24°C) position. Place right air temperature switch assembly in neutral position. Using scan tool, observe RIGHT and LEFT SOLAR SENSOR data parameters in IPM open/short data list. If scan tool indicates that RIGHT and LEFT SOLAR SENSOR data parameters are greater than 224 counts, go to next step. If scan tool indicates RIGHT and LEFT SOLAR SENSOR data parameters are less than 224 counts, go to step 17.
10. Uncover sunload sensor assembly. Direct a light source at right and then left side of sunload sensor assembly. If counts change similarly and correspond to proper side of sunload sensor assembly, go to next step. If counts do not change similarly and/or do not correspond to proper side of sunload sensor assembly, go to step 17.
11. Install a thermometer near air temperature sensors. Using scan tool, observe RIGHT AC DUCT TEMP, RIGHT HTR. DUCT TEMP, LEFT AC DUCT TEMP, LEFT HTR. DUCT TEMP, INSIDE AIR TEMP data parameters in IPM HVAC sensor data list. If scan tool indicate sensor temperatures are near thermometer temperatures within - 5 to +5°F (- 3 to +3°C), go to next step. If scan tool indicate sensor temperatures are not near thermometer temperatures within - 5 to +5°F (- 3 to +3°C), go to step 14.
12. If customer needs to change set temperature frequently to maintain comfort, go to «TEST M: SYSTEM DOES NOT MAINTAIN SET TEMPERATURE»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__test-m-system-does-not-maintain). If customer does not need to change set temperature frequently to maintain comfort, go to step 16.
13. Check aspiration hose for a blocked or disconnection. Repair as necessary, then go to step 22.
14. Inspect harness connector of suspect temperature sensor for poor connections. Repair as necessary, then go to step 22. If connections are okay, go to next step.
15. Test suspect temperature sensor resistance. (Scheme 9) If resistance measures near specification, go to step 18. If resistance does not measure near specification, go to step 19.
16. Install scan tool. Turn ignition on. Using scan tool, adjust TEMPERATURE OFFSET in IPM special function/set options as needed. After adjustment, go to step 22.
17. Inspect harness connector of sunload sensor assembly for poor connections. Repair as necessary, then go to step 22. If connections are okay, go to step 20.
18. Inspect harness connector of IPM for poor connections. Repair as necessary, then go to step 22. If connections are okay, go to step 21.
19. Replace suspect temperature sensor. See «AIR TEMPERATURE SENSORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 22.
20. Replace sunload sensor assembly. See «SUNLOAD SENSOR»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under REMOVAL & INSTALLATION. After repairs are complete, go to step 22.
21. Replace IPM. See INSTRUMENT PANEL INTEGRATION MODULE under REMOVAL & INSTALLATION in APPROPRIATE BODY CONTROL MODULES article IN accessories & equipment. After repairs are complete, go to next step.
22. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step 2.

Scheme 9

REMOVAL & INSTALLATION

Removal

1. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the negative battery cable.
2. Remove the positive battery cable nut and cable from the underhood fuse block. (Scheme 10) Disconnect the evaporator hose from the accumulator cover. (Scheme 11)
3. Remove the accumulator cover. (Scheme 12) Remove the A/C compressor hose nut from the accumulator. (Scheme 13)
4. Disconnect the A/C compressor hose from the accumulator. Remove the evaporator hose nut from the accumulator. (Scheme 14)
5. Remove the evaporator hose from the accumulator. Remove the accumulator from the housing.

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Installation

1. Add the proper amount of refrigerant oil to the accumulator. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__specifications). Install the accumulator into the housing. (Scheme 15)
2. Install NEW sealing washers. Connect the evaporator hose to the accumulator. (Scheme 14)
3. Install and tighten the evaporator hose nut. Connect the A/C compressor hose to the accumulator. (Scheme 13)
4. Install the A/C compressor hose nut. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the accumulator cover. (Scheme 12)
5. Connect the evaporator hose into the retainer. (Scheme 11) Install the positive battery cable and nut to the underhood fuse block.
6. Connect the negative battery cable. (Scheme 10) Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Leak test the fittings of the component. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.

Scheme 15

Removal (Left)

1. Remove the left side sound insulator. Remove the knee bolster. Remove the Instrument Panel Module (IPM).
2. Disconnect the electrical connector from the air temperature actuator. Remove the air temperature actuator retaining screws. (Scheme 16) Remove the air temperature actuator. (Scheme 17)

Scheme 16

Scheme 17

Removal (Right)

1. Remove the I/P compartment. Disconnect the electrical connector from the air temperature actuator.
2. Remove the air temperature actuator retaining screws. (Scheme 18) Remove the air temperature actuator. (Scheme 19)

Scheme 18

Scheme 19

Installation (Left)

1. Install the air temperature actuator. (Scheme 16) Install the driver air mix retaining screws. (Scheme 17) Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Connect the electrical connector to the air temperature actuator.
2. Install the IPM. Install the knee bolster. Install the left side sound insulator. Recalibrate the actuator. See «RECALIBRATING ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS.

Installation (Right)

1. Install the air temperature actuator. (Scheme 19) Install the passenger air mix retaining screws. (Scheme 18) Tighten to specified torque. Connect the electrical connector to the air temperature actuator.
2. Install the I/P compartment. Recalibrate the actuator. See «RECALIBRATING ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS.

Removal (Lower)

Remove the sound insulator. Disconnect the electrical connector from the sensor. Remove the sensor by turning 1/4 turn counter clockwise. (Scheme 20)

Scheme 20

Removal (Upper)

Remove the instrument panel storage compartment. Remove the sensor by twisting 1/4 turn counter clockwise. (Scheme 21) Disconnect the electrical connector from the air temperature sensor.

Scheme 21

Installation (Lower)

Connect the electrical connector to the sensor. Install the sensor into the sound insulator and turn 1/4 turn clockwise. (Scheme 20) Install the sound insulator.

Installation (Upper)

Connect the electrical connector to the air temperature sensor. Install the air temperature sensor into the duct and twist clockwise to lock in place. (Scheme 21) Install the instrument panel storage compartment

Remove the passenger window switch plate by prying up on the forward edge with a flat blade tool. (Scheme 22) Disconnect the electrical connector. Carefully push the tabs (1) on the passenger temperature control to remove from the switch plate. (Scheme 23)

Scheme 22

Scheme 23

Install the passenger temperature control ensuring the tabs are seated into the switch plate. (Scheme 23) Connect the electrical connector. Install the passenger window switch plate.

Disconnect the electrical connector from the ambient air temperature sensor. Remove the retainer and the ambient air temperature sensor. (Scheme 24) To install. Reverse removal procedure.

Scheme 24

1. Remove the left side sound insulator. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT Remove the aspirator hose at the muffler.
2. Remove the aspirator mounting bolt. Use a flat blade tool to pry the aspirator out of the HVAC case. (Scheme 25)

Scheme 25

1. Install the aspirator into the case. Install the bolt. (Scheme 25) Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Connect the aspirator hose to the muffler. Install the left side sound insulator.

1. Remove the right side sound insulator. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Pull back the carpet near the blower motor.
2. Remove the I/P compartment. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Remove the Dash Integration Module (DIM) from the bracket. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. Remove the 2 rear DIM bracket screws. (Scheme 26)
3. Reposition the DIM bracket to allow for removal of the blower motor. Disconnect the electrical connector from the blower motor. Remove the blower motor retaining screws. (Scheme 27)
4. Lower the blower motor and rotate counterclockwise to remove from the vehicle.

Scheme 26

Scheme 27

1. Install the blower motor. Blower motor will need to be rotated to install into the housing. Install the blower motor retaining screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Connect the electrical connector to the blower motor. (Scheme 27)
2. Reposition the DIM bracket to its original position. Install the 2 rear DIM bracket screws. (Scheme 26) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
3. Install the DIM into the bracket. Install the I/P compartment.
4. Reposition the carpet. Install the right side sound insulator.

1. Remove the right side sound insulator. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Disconnect the electrical connector from the blower motor. Disconnect the blower ventilation tube from the module. (Scheme 28)
2. Remove the blower motor screws. Remove the blower motor from the housing. (Scheme 29)

Scheme 28

Scheme 29

1. Install the blower motor into the housing. Install the blower motor screws. (Scheme 29) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Install the blower ventilation tube to the module. Connect the blower motor electrical connector. (Scheme 28) Install the right side sound insulator.

1. Remove the right sound insulator. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Remove the instrument panel compartment. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
2. Remove the Dash Integration Module (DIM) from the bracket and position aside. Remove the rear DIM bracket screws and lower the bracket enough to access the blower module.
3. Disconnect the electrical connector. (Scheme 30) Remove the blower motor control processor retaining screw. Remove the blower motor control processor.

Scheme 30

1. Install the blower control module. Install the retaining screw. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Connect the electrical connector. (Scheme 30) Install the DIM bracket screws. Tighten to specification.
3. Install the DIM into the bracket. Install the instrument panel compartment.
4. Install the right sound insulator. Recalibrate the actuator. See «CALIBRATING ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS.

COMPRESSOR

Note. For all compressor repair operations, see COMPRESSOR SERVICING article in GENERAL SERVICING.

1. Recover the refrigerant from the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the negative battery cable.
2. Remove the accessory drive belt. Remove the right wheelhouse extension.
3. Remove the lower air deflector. Disconnect the electrical connector from the compressor. (Scheme 31)
4. Disconnect the electrical connector from the A/C pressure sensor. Remove the retaining bolt from the wiring harness bracket. (Scheme 32)
5. Remove the A/C compressor hose nut. Remove the A/C compressor hose from the compressor. (Scheme 33)
6. Remove the front compressor mounting nuts. Remove the rear compressor mounting bolt. (Scheme 34) Remove the compressor.
7. If replacing the compressor, drain and measure as much of the oil as possible from the removed compressor: Drain the oil from both the suction and discharge ports of the removed compressor into a clean container. Remove the compressor crankcase oil drain plug and drain the crankcase oil into the same container. Measure and record the amount of oil drained from the removed compressor. This measurement will be used during installation of the replacement compressor. Properly dispose the used PAG oil.

Scheme 31

Scheme 32

Scheme 33

Scheme 34

Note. Inspect the seal washers for damage before reinstalling the A/C lines and hoses. If any damage is noted during inspection, the suspect seal must be replaced. Flat washer type seals do not require lubrication.

1. Install the compressor. Install the front mounting nuts and the bolt. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Install the rear bolt to the compressor. Tighten to specification. Install the A/C compressor hose to the compressor. (Scheme 33)
3. Install the A/C compressor hose nut. Tighten to specification. Connect the electrical connector to the compressor. (Scheme 31)
4. Connect the electrical connector to the A/C pressure sensor. Install the retaining bolt to the wiring harness bracket. (Scheme 32) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Lower the vehicle.
5. Install the accessory drive belt. Connect the negative battery cable.
6. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
7. Leak test the repair. See LEAK TESTING article in GENERAL SERVICING. Install the lower air deflector. Install the right wheelhouse extension.

1. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the negative battery cable.
2. Disconnect the electrical connector from the A/C pressure switch. (Scheme 31) Remove the A/C compressor hose nut at the compressor. (Scheme 33) Disconnect the A/C compressor hose assembly from the compressor.
3. Remove the A/C compressor hose nut at the condenser. Disconnect the A/C compressor hose assembly from the condenser. (Scheme 35)
4. Remove the A/C compressor hose nut at the accumulator. (Scheme 14) Disconnect the A/C compressor hose from the accumulator. Remove the A/C compressor hose from the vehicle. Remove the A/C refrigerant pressure sensor from the hose.

Scheme 35

Note. Inspect the seal washers for damage before reinstalling the A/C lines and hoses. If any damage is noted during inspection, the suspect seal must be replaced. Flat washer type seals do not require lubrication.

1. Install the A/C refrigerant pressure sensor to the hose. Install the A/C compressor hose to the vehicle. Connect the A/C compressor hose to the A/C compressor. (Scheme 33) Install the A/C compressor hose nut. Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Connect the electrical connector to the A/C pressure switch. (Scheme 31) Connect the A/C compressor hose to the condenser. Install the A/C compressor hose nut. (Scheme 35) Tighten to specified torque.
3. Install the A/C compressor hose and nut to the accumulator. (Scheme 13) Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Connect the negative battery cable. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.

Remove the electrical center cover. Remove the A/C compressor relay from the electrical center. (Scheme 36)

Install the A/C compressor relay to the electrical center. (Scheme 36) Install the electrical center cover.

Scheme 36

1. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Remove the upper tie bar support brace bolts at the upper tie bar.
2. Loosen the support brace bolts at the headlight and bumper fascia mounting panel and position out of the way. Remove the upper radiator seal. (Scheme 37)
3. Remove the upper radiator mounting brackets. (Scheme 38) Disconnect the compressor hose from the condenser. (Scheme 35)
4. Remove the front headlight. Disconnect the evaporator hose from the condenser. (Scheme 39)
5. Remove the fasteners from the left and right sides of the headlight and bumper fascia mounting panel. (Scheme 40) Lift the headlight and bumper fascia mounting panel and pull forward in car to obtain access to the condenser mounting bolts.
6. Remove the 2 condenser to radiator mounting bolts. Separate the condenser from the radiator by lifting out of the lower mounting tabs. Disconnect and remove the low coolant sensor (vehicles with gauges - RPO UB7 only).
7. Remove the 2 A/C condenser seals. (Scheme 41) Lift the condenser up and remove from the vehicle.

Scheme 37

Scheme 38

Scheme 39

Scheme 40

Scheme 41

1. Add the proper amount of refrigerant oil to the NEW condenser. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__specifications). Position the condenser into the vehicle.
2. Install and connect the low coolant sensor and wiring harness (vehicles with gauges - RPO UB7 only). Install the condenser into the lower radiator mounting tabs.
3. Install the condenser mounting bolts. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the NEW A/C condenser seals. (Scheme 41)
4. Reposition the headlight and bumper fascia mounting panel and install the fasteners. (Scheme 40) Tighten to specification. Install NEW seal washers.
5. Install the evaporator hose and nut to the condenser. (Scheme 39) Install the compressor hose and nut to the condenser. (Scheme 35) Tighten to specification.
6. Install the upper radiator mounting brackets and bolts. (Scheme 38) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the upper radiator seal. (Scheme 37)
7. Install the front fascia to tie bar support brackets and bolts. Tighten to specification. Install the front headlight.
8. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.

1. Remove the HVAC module assembly. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic). Remove the seal from around the heater core and the evaporator tubes. (Scheme 42)
2. Remove the upper HVAC evaporator case screws. Separate the HVAC evaporator case halves. Remove the evaporator core. (Scheme 43)

Scheme 42

Scheme 43

1. Add the proper amount of refrigerant oil to the evaporator. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__specifications). Install the evaporator core into the module housing. (Scheme 43)
2. Install the upper HVAC module case. Install the upper HVAC module screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
3. Install the seal over the heater core and the evaporator pipes. (Scheme 42) Install the HVAC assembly. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic).

HEATER CORE (WITHOUT CONSOLE)

Note. Tools Required: Hose Clamp Pliers (J-38185).

1. Drain the cooling system. Remove the fuel injector sight shield.
2. Position the Hose Clamp Pliers in order to remove the heater hose clamps. (Scheme 44) Remove the heater hoses from the heater core.
3. Remove the left side sound insulator. Remove the right side sound insulator.
4. Remove the air distributor duct screws. Remove the air distributor duct. (Scheme 45)
5. Remove the heater core heat shield screws. Remove the heater core heat shield. Remove the heater core cover screws. (Scheme 46)
6. Remove the heater core cover. Remove the retaining screw and strap from the heater core. Remove the heater core.

Scheme 44

Scheme 45

Scheme 46

1. Install the heater core into the HVAC module. Secure the heater core into the HVAC module using the attaching straps and screws. Tighten to specification. See TORQUE SPECIFICATIONS. Install the heater core cover.
2. Ensuring the seals at the front of dash are in the proper positions, install the heater core cover screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the heater core heat shield.
3. Install the heater core heat shield screws. (Scheme 46) Tighten to specification. Install the air distributor duct.
4. Install the air distributor duct left side screw. (Scheme 45) Ensure the right tab is seated properly. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the left side sound insulator. Install the right side sound insulator.
5. Install the heater hoses and clamps using Hose Clamp Pliers. (Scheme 44) Install the fuel injector sight shield. Fill the cooling system.

HEATER CORE (WITH CONSOLE)

Note. Tools Required: Hose Clamp Pliers (J-38185).

1. Drain the cooling system. Remove the fuel injector sight shield. Position the Hose Clamp Pliers in order to remove the heater hose clamps. (Scheme 44) Remove the heater hoses from the heater core.
2. Remove the left side sound insulator. Remove the right side sound insulator. Remove the auxiliary air distribution duct adapter. (Scheme 47)
3. Remove the air distributor duct screws. (Scheme 48) Remove the air distributor duct.
4. Remove the heater core heat shield screws. (Scheme 46) Remove the heater core heat shield. Remove the heater core cover screws.
5. Remove the heater core cover. Remove the retaining screw and strap from the heater core. Remove the heater core.

Scheme 47

Scheme 48

1. Install the heater core into the HVAC module. Secure the heater core into the HVAC module using the attaching straps and screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the heater core cover.
2. Ensuring the seals at the front of dash are in the proper positions, install the heater core cover screws. Install the heater core heat shield and screws. (Scheme 46) Tighten to specification.
3. Install the air distributor duct. Install the air distributor duct left side screw. (Scheme 48) Ensure the right side tab is seated properly. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
4. Install the auxiliary air distribution duct adapter. (Scheme 47) Install the left side sound insulator. Install the right side sound insulator.
5. Install the heater hoses and clamps using the Hose Clamp Pliers. (Scheme 44) Install the fuel injector sight shield. Fill the cooling system.

Remove the right I/P accessory trim plate. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Pinch the tabs on the control module and pull rearward on the HVAC control module to remove from the I/P. (Scheme 49)

Scheme 49

Note. The ignition must be in the OFF position when installing the HVAC control module to ensure proper actuator calibration.

Note. Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted improper HVAC performance will result. The engine must be running for proper calibration to occur.

Install the HVAC control module and ensure that the tabs are fully seated to the I/P. (Scheme 49) Install the right I/P accessory trim plate. Start the vehicle and let run for one minute to calibrate.

1. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Drain the coolant.
2. Remove the evaporator hose nut. (Scheme 50) Disconnect the evaporator hose connection at the evaporator.
3. Remove the heater hoses from the heater core using the hose clamp pliers. (Scheme 51) Plug the heater core and evaporator openings to prevent leaking into the vehicle when removing module assembly.
4. Remove the I/P assembly. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Remove the defroster duct retaining screws. Remove the defroster duct nut. (Scheme 52)
5. Remove the defroster duct. Remove the air distributor duct screws. Remove the air distributor duct.
6. Disconnect the blower control module connection. Disconnect the I/P to HVAC module connection. (Scheme 30) Remove the HVAC module retaining nuts. Remove the HVAC module. (Scheme 53)

Scheme 50

Scheme 51

Scheme 52

Scheme 53

1. Install the HVAC module. Install the HVAC module nuts to the dash. See the illustration for the HVAC module fastener torque sequence. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). (Scheme 53)
2. Connect the blower control module connection. Connect the I/P harness to HVAC module connector. (Scheme 30) Install the defroster duct.
3. Install the defroster duct module mounting screws. Install the defroster duct mounting nut to the front of dash. (Scheme 52) Tighten to specification. Install the air distributor duct.
4. Install the air distributor duct screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the I/P assembly. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
5. Install the heater hoses to the heater core using the hose clamp pliers. (Scheme 51) Install NEW seal washers to the fitting.
6. Connect the evaporator hose connection to the evaporator. (Scheme 50) Install the evaporator hose nut. Tighten to specification. See T «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
7. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Leak test the component. Refill the engine coolant.

1. Remove the right I/P trim plate. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Remove the knee bolster.
2. Pull rearward on the aspirator hose to disengage from the IP. Remove the temperature sensor from the aspirator hose by turning 1/4 turn counter clockwise. (Scheme 54) Disconnect the temperature sensor electrical connector.

Scheme 54

1. Connect the temperature sensor electrical connector. Install the inside air temperature sensor to the aspirator hose and turn clockwise 1/4 turn.
2. Install the aspirator hose into the instrument panel. (Scheme 54) Install the knee bolster. Install the cluster trim plate.

1. Remove the air temperature actuator. See «AIR TEMPERATURE ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic). Disconnect the electrical connector from the mode actuator. Remove the IPM. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
2. Remove the mode actuator retaining screws. (Scheme 55) Remove the mode actuator.

Scheme 55

1. Align the mode valve levers with the cam slots. Install the mode actuator. Install the mode actuator retaining screws. (Scheme 55) Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Connect the electrical connector to the mode actuator. Install the IPM. Install the air temperature actuator. See «AIR TEMPERATURE ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic). Recalibrate the actuator. See «RE-CALIBRATING ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS.

1. Remove the HVAC Module. See HVAC MODULE ASSEMBLY. Remove the mode actuator screws. Remove the mode actuator.
2. Remove the left temperature actuator screws. Remove the left temperature actuator. Remove the screws that retain the mode actuator bracket. Remove the mode actuator bracket.
3. Remove the upper module case screws in order to access the door. Open the module. (Scheme 56)
4. Remove the actuator cam from the door. (Scheme 57) Remove the mode door. (Scheme 58)

Scheme 56

Scheme 57

Scheme 58

1. Install the mode door. Install the actuator cam to the mode door. (Scheme 58)
2. Close the module case. (Scheme 56) Install the module case screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the mode actuator and bracket.
3. Install the mode actuator screws. Tighten to specification. Install the left temperature actuator.
4. Install the actuator screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the HVAC module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic).

1. Remove the HVAC Module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic). Remove the mode actuator screws. Remove the mode actuator.
2. Remove the left temperature actuator screws. Remove the left temperature actuator. Remove the screws that retain the mode actuator bracket. Remove the mode actuator bracket.
3. Remove the upper module case screws in order to access the door. Open the module. Remove the actuator cam from the door. (Scheme 57)
4. Remove the spring from the upper mode door. (Scheme 59) Remove the upper mode door.

Scheme 59

1. Install the upper mode door. Attach the spring to the upper mode door. (Scheme 59)
2. Install the actuator cam to the mode door. (Scheme 57) Close the module case. Install the module case screws.
3. Install the mode actuator and bracket. Install the actuator screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the left temperature actuator.
4. Install the actuator screws. Tighten to specification. Install the HVAC module.

1. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the A/C evaporator hose from the retaining clips. (Scheme 11)
2. Separate the A/C evaporator hose at the orifice tube location. (Scheme 60) Remove the orifice tube from the line. (Scheme 61)

Scheme 60

Scheme 61

Note. Lubricate the NEW orifice tube O-ring with mineral base 525 viscosity refrigerant oil before installing into the evaporator hose.

Note. Ensure that the short screen and arrow face toward the evaporator.

1. Install the NEW orifice tube. (Scheme 61) Connect the A/C evaporator tube and tighten. (Scheme 60)
2. Install the A/C evaporator hose into the retaining clips. Recharge the A/C system.

Lift up the access cover in the air inlet panel. Remove the filter from the filter housing. (Scheme 62) To install, reverse removal procedure.

Scheme 62

1. Remove the I/P compartment. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Remove the right sound insulator.
2. Remove the Dash Integration Module (DIM) from the bracket. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Remove the rear 2 DIM module bracket screws. (Scheme 26)
3. Reposition the DIM module bracket to gain access to the recirculation actuator. Disconnect the electrical connector from the recirculation actuator.
4. Remove the recirculation actuator retaining screws. Remove the recirculation actuator. (Scheme 19)

1. Install the recirculation actuator. (Scheme 19) Install the recirculation actuator retaining screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Connect the electrical connector to the recirculation actuator. Position the DIM module bracket to its original position. (Scheme 26) Install the rear 2 DIM module bracket retaining screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
3. Install the DIM module into the bracket. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Install the right sound insulator.
4. Install the I/P compartment. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Recalibrate the actuator. See «CALIBRATING ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic) under ADJUSTMENTS.

1. Remove the HVAC Module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic). Remove the recirculation housing screws. (Scheme 63)
2. Remove the recirculation housing. Remove the recirculation door from the housing.

Scheme 63

1. Install the recirculation door into the housing. Install the recirculation housing. (Scheme 63)
2. Install the recirculation housing screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Install the HVAC module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic).

1. Disconnect the electrical connector from the A/C refrigerant pressure sensor. (Scheme 31)
2. Unscrew and remove the A/C refrigerant pressure sensor. Remove the O-ring seal.

1. Lubricate the NEW O-ring using 525 refrigerant oil. Install the O-ring seal.
2. Install the A/C refrigerant pressure sensor. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications). Connect the electrical connector to the A/C refrigerant pressure sensor. (Scheme 31)

Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. (Scheme 64)

Scheme 64

1. Lubricate the O-ring using 525 refrigerant oil. Install the service fitting to the line. (Scheme 64) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/automatic-hvac-system/#hvac-systems-automatic__torque-specifications).
2. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.

Remove the defroster grille by carefully prying upward in order to release the retainers. Disconnect the electrical connector from the sensor. Twist the sensor counterclockwise to remove. (Scheme 65) To install, reverse removal procedure.

Scheme 65

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 66

Scheme 67

Scheme 68

Scheme 69

Scheme 70

Scheme 71

Scheme 72

Scheme 73

Scheme 74

Scheme 75

WIRING DIAGRAMS

See AIR CONDITIONING in SYSTEM WIRING DIAGRAMS article in WIRING DIAGRAMS.

See also:
• TROUBLE SHOOTING
• DIAGNOSTIC TROUBLE CODE DEFINITIONS
• SYMPTOM DIAGNOSIS
• COMPUTERIZED ENGINE CONTROLS
• A/C PRESSURE ZONE "A" DIAGNOSIS
• A/C PRESSURE ZONE "B" DIAGNOSIS
• A/C PRESSURE ZONE "C" DIAGNOSIS
• A/C PRESSURE ZONE "D" DIAGNOSIS
• TROUBLE SHOOTING
• TEST O: TOO COLD IN VEHICLE
• REMOVAL & INSTALLATION
• DIAGNOSTIC SYSTEM CHECK
• HEATER CORE (WITHOUT CONSOLE)
• HEATER CORE (WITH CONSOLE)
• DIAGNOSTIC TROUBLE CODE IDENTIFICATION
• SYMPTOM TESTS
• CLEARING TROUBLE CODES
• B0126
• B0131
• B0159
• B0164
• B0174
• B0179
• B0184 Or B0189
• B0234
• B0237
• B0249
• B0252
• B0269
• B0272
• B0279
• B0282
• B0490
• B1000
• B2805
• P0530
• P1536
• P1540
• DESCRIPTION & OPERATION
• WIRING DIAGRAMS
• TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE
• A/C PERFORMANCE TEST
• SPECIFICATIONS
• COMPRESSOR
• A
• B
• C
• D
• E
• G
• H
• I
• J
• K
• L
• M
• N
• P
• HEATER PERFORMANCE TEST
• TORQUE SPECIFICATIONS