HVAC Systems - Manual Buick LeSabre VIII

SPECIFICATIONS

SPECIFICATIONS

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 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a zero-12 volt linear-ramped signal to command the actuator movement. The zero and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between zero and 12 volts correspond to the positions between the limits. When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between zero-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed.

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 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.

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. 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. Once a blower speed is selected, the blower speed remains constant until a NEW speed is selected. 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.

Air Distribution

The HVAC control module controls the mode actuator in order to distribute airflow to a desired outlet. 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.

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 three 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.

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.

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 a very low temperature gas that can transfer the undesirable heat and moisture from the passenger compartment to the outside air. The A/C system used on this vehicle is a non-cycling system. Non-cycling A/C systems use a high-pressure switch to protect the A/C system from excessive pressure. The high-pressure switch will open the electrical signal to the compressor clutch, if the refrigerant pressure becomes excessive. After the high and the low sides of the A/C system pressure equalize, the high-pressure switch will close. This completes the electrical circuit to the compressor clutch.

The A/C system is also 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 continues to rise, the high-pressure relief will pop open and release refrigerant from the system. 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. The refrigerant is discharged from the compressor through the discharge hose, and forced through the condenser and then through the balance of the A/C system. Compressed refrigerant enters the condenser at a high-temperature, high-pressure vapor state. As the refrigerant flows through the condenser, the heat is transferred to the ambient air passing through the condenser. Cooling 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, causing the refrigerant to vaporize at the orifice tube. The orifice tube also measures 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 to boil inside 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 flows back to the compressor in a vapor state, 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 condenses, and discharges from the HVAC module as water.

HVAC CONTROL MODULE

The HVAC control module is a Class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The ignition 3 and battery positive voltage circuits provide power to the control module.

HVAC OPERATIONS

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 A/C system can be engaged by pressing the A/C switch. The A/C system is engaged when the HVAC control module is in any mode except VENT and HTR. The A/C switch will illuminate when the A/C switch is pressed to the on position. The control module sends a Class 2 A/C request message to the Dash Integration Module (DIM). In order for the Powertrain Control Module (PCM) to turn on the compressor clutch, the DIM and PCM must communicate to each other over the Class 2 serial data circuits. The following conditions must be met in order for the PCM to turn on the compressor clutch

1. DIM Battery voltage 9-18 volts. A/C request from the HVAC control module. Engine coolant temperature (ECT) is less than 250°F (121°C).
2. PCM Engine coolant temperature (ECT) is less than 250°F (121°C). Engine speed is less than 5000 RPM. A/C Pressure is between 35-430 psi (255-2968 kPa).

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 250°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.

MODE ACTUATOR

The mode actuator is a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a zero-12 volt linear-ramped signal to command the actuator movement. The zero and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between zero and 12 volts correspond to the positions between the limits. When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between zero-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a NEW commanded value is needed.

RECIRCULATION ACTUATOR

The recirculation actuator is a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit is either grounded or opened during normal operation. If the control circuit is grounded, then the shaft rotates in the opposite direction than it would if the circuit was opened. The actuator shaft rotates until the limit is reached. If the module needs to reverse the direction of rotation, then the control circuits state is reversed. The open circuits are held at ignition 3 voltage from the actuator. The module will maintain the control circuits state until a new position is needed.

COMPONENT LOCATIONS

COMPONENT LOCATIONS

Scheme 1

Scheme 2

Scheme 3

CALIBRATING ACTUATORS

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

Use the following steps to perform the calibration update

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

PRELIMINARY INSPECTION

Verify customers complaint. Before performing any testing, perform a visual inspection. Check system fuses. Check connectors for loose, damaged or corroded terminals. Check for damaged wiring harness. Check for damaged or binding actuator cable. If area of fault cannot be located or repaired during preliminary inspection, check self-diagnostic system. See SELF DIAGNOSTIC SYSTEM . Repair as necessary.

If no problem is found, attempt diagnosis by symptom. See SYMPTOM DIAGNOSIS .

Note. Use the following symptoms to aid in preliminary diagnosis. If a listed symptom matches the customers concern, check the applicable items for possible cause.

SYMPTOM DIAGNOSIS

Note. Perform PRELIMINARY INSPECTION prior to diagnosing by symptom.

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the HVAC System. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom. Verify the A/C compressor clutch turns freely and is not seized. The A/C compressor will not operate in cold ambient air temperatures. The following conditions may cause window fogging

1. Wet carpet or mats.
2. High humidity.
3. Interior water leak.
4. Blocked A/C evaporator drain tube.
5. Maximum passenger capacity.
6. Blocked body pressure relief valves.

Inspect the air distribution system for causes of reduced air flow

1. Obstructed or dirty passenger compartment air filter, if equipped.
2. Blocked or damaged air inlet or outlet vents.

Intermittents

Faulty electrical connections or wiring may be the cause of intermittent conditions. See WIRING DIAGRAMS .

Symptom List

See a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. HVAC Compressor Clutch Does Not Engage
2. HVAC Compressor Clutch Does Not Disengage
3. Blower Motor Always On
4. Blower Motor Inoperative
5. Blower Motor Malfunction
6. Too Hot in Vehicle
7. Too Cold in Vehicle
8. Air Delivery Improper
9. Air Recirculation Malfunction

For symptom testing, see

SYMPTOM TESTS

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 at least 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 2000 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 step 2. 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: The A/C On. Recirculation mode. 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/transmission in the PARK (Automatic) or NEUTRAL (Manual) 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. 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 4) 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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__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 «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLE SHOOTING.

Scheme 4

HEATER PERFORMANCE TEST

1. Were you sent here from TOO COLD IN VEHICLE? If so, go to step 2 . If not, go to «TEST I: TOO COLD IN VEHICLE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-i-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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__heater-core-without-console) or «HEATER CORE (WITH CONSOLE)»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__heater-core-with-console) under REMOVAL & INSTALLATION. After repairs are complete, go to step 10 .
9. Repair the low engine temperature concern (possible stuck-open or missing thermostat). 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 .

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/manual-hvac-system/#hvac-systems-manual) .
2. Install a scan tool. Does the scan tool power up? If so, go to next step. If not, see 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 PCM. Does the scan tool communicate with the PCM? If so, go to step 4 . If not, see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
4. Select the PCM display DTCs function on the scan tool. Does the scan tool display any DTCs? If so, go to next step. If not, go to «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLESHOOTING.
5. 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.
6. Does the scan tool display any DTCs which begin with a "P" that are associated with the HVAC system? If so, go to «DIAGNOSTIC TESTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) . If not, see appropriate SELF-DIAGNOSTIC article in ENGINE PERFORMANCE.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Diagnosis of temperature control portion of HVAC system is based on Diagnostic Trouble Codes (DTCs) stored in HVAC control module. The HVAC control module will store either a current or history DTC depending on type of fault detected.

For system diagnosis, use a scan tool to check for any DTCs that may be set. If a DTC is set, go to appropriate diagnostic procedure. See DIAGNOSTIC TROUBLE CODE INDEX table. After a repair is completed, DTCs must be cleared from memory to ensure proper system operation. See CLEARING DIAGNOSTIC TROUBLE CODES . If no DTCs are set, diagnose problem by symptom, see SYMPTOM TESTS .

DIAGNOSTIC TROUBLE CODE INDEX

CLEARING DIAGNOSTIC TROUBLE CODES

Diagnostic Trouble Codes (DTCs) are cleared using a scan tool. After repairs are made, clear DTCs following scan tool manufacturers instructions. If a scan tool is not available, DTCs are automatically cleared from memory after 100 drive cycles if no faults are present. A drive cycle occurs each time vehicle is started, then driven at a speed greater than 10 MPH.

DTC P0530: A/C PRESSURE SENSOR CIRCUIT FAULT

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

Circuit Description

The A/C system uses an A/C refrigerant pressure sensor mounted in the high-pressure side of the A/C refrigerant system to monitor A/C refrigerant pressure. The Powertrain Control Module (PCM) uses this information to turn on the engine coolant fans when the A/C refrigerant pressure is high and to keep the compressor disengaged when A/C refrigerant pressure is excessively high or low. The A/C refrigerant pressure sensor operates like other 3 wire sensors. The PCM applies a 5-volt reference and a sensor ground to the sensor. Changes in the A/C refrigerant pressure will cause the A/C refrigerant pressure input to the PCM to vary. The PCM monitors the A/C refrigerant pressure sensor signal circuit and can determine when the signal is outside of the possible range of the sensor. When the signal is out of range (high or low) for a prolonged period of time, the PCM will set DTC P0530. When the DTC P0530 is set, the PCM will not allow the A/C compressor clutch to engage. This is done to protect the compressor.

Conditions For Running DTC

The engine is running.

Conditions For Setting DTC

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 4.9 volts.
3. Either of the above conditions are present for more than 20 seconds.

Action Taken When the DTC Sets

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.

Conditions for Clearing the DTC

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. Use a scan tool in order to clear the diagnostic trouble code.

Diagnostic Aids

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 problem is intermittent, See INTERMITTENTS under TROUBLE SHOOTING.

Diagnostic Procedure

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to step 2 . If no go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn the ignition off. Inspect the A/C compressor for free rotation operation. Start the engine. Place the HVAC Control Module in the OFF position. Does the A/C compressor operate? If so, go to «TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-f-compressor-clutch-does-not) under SYMPTOM TESTS. If not, go to next step.
3. Install a scan tool. Turn ignition on. With a scan tool, observe the A/C HIGH SIDE PRESSURE parameter in the PCM ENGINE DATA 2 LIST. Does the scan tool indicate that the A/C HIGH SIDE PRESSURE parameter is 0.1-4.9 volts? If so, go to «DIAGNOSTIC AIDS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-aids) . If not, go to next step.
4. Turn the ignition off. Disconnect the A/C refrigerant pressure sensor. Turn ignition on. With a scan tool, observe the A/C HIGH SIDE PRESSURE parameter in the PCM ENGINE DATA 2 LIST. Does the scan tool indicate that the A/C HIGH SIDE PRESSURE parameter is less than the specified value? If so, go to next step. If not, go to step 11 .
5. Turn the ignition off. Connect a 3-amp fused jumper wire between the 5 volt reference circuit and the A/C refrigerant pressure sensor signal circuit of the A/C refrigerant pressure sensor. Turn ignition on. With a scan tool, observe the A/C HIGH SIDE PRESSURE parameter in the PCM ENGINE DATA 2 LIST. Does the scan tool indicate that the A/C HIGH SIDE PRESSURE parameter is greater than 4.9 volts? If so, go to NEXT step. If not, go to step 9 .
6. Disconnect the fused jumper wire. Measure the voltage between the 5-volt reference circuit and the low reference circuit of the A/C refrigerant pressure sensor. Does the voltage measure less than 5.0 volts? If so, go to next step. If not, go to step 8 .
7. Turn the ignition off. Disconnect the negative battery cable. Measure the resistance from the low reference circuit of the A/C refrigerant pressure sensor to ground. Does the resistance measure less than 5.0 ohms? If so, go to step 12 . If not, go to step 13 .
8. Check the 5-volt reference circuit of the A/C refrigerant pressure sensor for short to voltage. Did you find and correct the condition? If so, go to step 17 . If not, go to step 14 .
9. Check the 5-volt reference circuit of the A/C refrigerant pressure sensor for a short to ground, a high resistance, or an open. Did you find and correct the condition? If so, go to step 17 . If not, go to next step.
10. Check the A/C refrigerant pressure sensor signal circuit of the A/C refrigerant pressure sensor for a short to ground, a high resistance, or an open. Did you find and correct the condition? If so, go to step 17 . If not, go to step 14 .
11. Check the A/C refrigerant pressure sensor signal circuit of the A/C refrigerant pressure sensor for a short to voltage. Did you find and correct the condition? If so, go to step 17 . If not, go to step 14 .
12. Disconnect the PCM. Check the low reference circuit of the A/C refrigerant pressure sensor for a high resistance or an open. Did you find and correct the condition? If so, go to step 17 . If not, go to step 14 .
13. Inspect for poor connections at the harness connector of the A/C refrigerant pressure sensor. Did you find and correct the condition? If so, go to step 17 . If not, go to step 15 .
14. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If so, go to step 17 . If not, go to step 16 .
15. Replace the A/C refrigerant pressure sensor. See «REFRIGERANT PRESSURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 17 .
16. Replace the 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 in ENGINE PERFORMANCE. After repairs are complete, go to next step.
17. Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. See «CONDITIONS FOR RUNNING DTC»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__conditions-for-running-dtc) . Does the DTC reset? If so, go to step 2 . If not, system is okay.

DTC P1536: ENGINE COOLANT OVERTEMPERATURE (A/C DISABLED)

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

The Powertrain Control Module (PCM) monitors the engine coolant temperature through the Engine Coolant Temperature (ECT) 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 compressor clutch engagement if the engine coolant temperature is too high. If the PCM determines that a fault is present in the coolant temperature 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 will not request the A/C clutch on.

Conditions For Clearing DTC

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

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 clutch 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 Inoperative thermostat.
5. Water pump failure.
6. Check the PCM for current or history engine coolant temperature sensor DTCs.
7. Trailer weight exceeding 1000 Lbs. (454 kg) in extreme high ambient temperatures.
8. Aftermarket products affecting cooling system performance.

1. Check the cooling system for proper operation. If okay, go to next step If not, repair cooling system malfunction.
2. Check the engine cooling fans for proper operation. Are the engine cooling fans operative? If so, check for cause of engine overheating. If not, go to appropriate ELECTRIC COOLING FANS article in ENGINE COOLING.

DTC P1540: A/C REFRIGERANT OVERPRESSURE (A/C DISABLED)

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

The A/C system uses an A/C refrigerant pressure sensor mounted in the high-pressure side of the A/C refrigerant system to monitor A/C refrigerant pressure. The Powertrain Control Module (PCM) uses this information to turn on the engine coolant fans when the A/C refrigerant pressure is high and to keep the compressor disengaged when A/C refrigerant pressure is excessively high or low. The A/C refrigerant pressure sensor operates like other 3 wire sensors. The PCM applies a 5 volt reference and a sensor ground to the sensor. Changes in the A/C refrigerant pressure will cause the A/C refrigerant pressure input to the PCM to vary. The PCM monitors the A/C refrigerant pressure sensor signal circuit. 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 and set DTC P1540.

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 201 psi (1386 kPa) 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 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. 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 the following conditions

1. An overcharged A/C system.
2. A failed A/C refrigerant pressure sensor.
3. Blockage in a refrigerant line.
4. Debris in front of the A/C condenser.
5. Radiator or A/C condenser air shields missing or out of location.
6. Inoperative engine cooling fans.
7. Extended periods at idle in city traffic followed by rapid acceleration.
8. Aftermarket products affecting cooling system performance.

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to step 2 . If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF DIAGNOSTIC SYSTEM.
2. Install a scan tool. Turn ignition on. Wait for one minute for A/C system pressure to equalize. With the scan tool, observe the current DTC list in the DASH INTEGRATION MODULE. Is DTC P1540 stored as current? If so, go to next step. If not, go to «DIAGNOSTIC AIDS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) .
3. Connect the ACR 2000 Air Conditioning Service Center. Observe the A/C pressure parameter in the DASH INTEGRATION MODULE A/C INFORMATION DATA LIST using the scan tool. Does the scan tool indicate system pressure near the gauge pressure within -20 to +20 psi (-138 to +138 kPa)? If so, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__ac-performance-test) under PERFORMANCE TESTS. If not, go to next step.
4. Replace the A/C refrigerant pressure sensor. See «REFRIGERANT PRESSURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
5. Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified. See «CONDITIONS FOR RUNNING DTC»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) . Does the DTC reset? If so, go to step 2 . If not, system is okay.

DTC P1546: COMPRESSOR CLUTCH RELAY CONTROL CIRCUIT FAULT

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 relay and ignition 3 voltage is supplied to the coil side of the A/C compressor relay. The Powertrain Control Module (PCM) controls the relay by grounding the A/C 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 is on.
2. The ignition voltage is between 9.0-18.0 volts.

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

1. The PCM will not illuminate the malfunction indicator lamp (MIL). The PCM will store conditions which were present when the DTC set as Failure Records data only.
2. 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.

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to step 2 . If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF DIAGNOSTIC SYSTEM.
2. Install a scan tool. Turn ignition on. With a scan tool, command the A/C Relay ON and OFF in the Special Functions, Engine Output Controls list. Does the A/C compressor relay turn ON and OFF with each command? If so, go to «DIAGNOSTIC AIDS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) . If not, go to step 3 .
3. Turn the ignition off. Disconnect the A/C compressor relay. Turn ignition on. Probe the ignition 3 voltage circuit of the A/C compressor relay with a test light that is connected to ground. Does the test light illuminate? If so, go to step 4 . If not, go to step 8 .
4. Connect a test light between the A/C compressor relay control circuit and the ignition 3 voltage circuit of the A/C compressor relay. With a scan tool, command the A/C Relay ON and OFF. Does the test light turn on and off with each command? If so, go to step 9 . If not, go to next step.
5. Does the test light remain illuminated with each command? If so, go to step 7 . If not, go to next step.
6. Check the A/C compressor relay control circuit for a short to voltage or an open. Did you find and correct the condition? If so, go to step 13 . If not, go to step 10 .
7. Check the A/C compressor relay control circuit of the A/C compressor relay for a short to ground. Did you find and correct the condition? If so, go to step 13 . If not, go to step 10 .
8. Repair the ignition 3 voltage circuit of the A/C compressor relay. After repairs are complete, go to step 13 .
9. Inspect for poor connections at the A/C compressor relay. Did you find and correct the condition? If so, go to step 13 . If not, go to step 11 .
10. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If so, go to step 13 . If not, go to step 12 .
11. Replace the A/C compressor relay. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
12. Replace the 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 the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified. Does the DTC reset? If so, go to step 2 . If not, system is okay.

A/C PRESSURE ZONE "A" DIAGNOSIS

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

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/manual-hvac-system/#hvac-systems-manual__ac-performance-test).
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/manual-hvac-system/#hvac-systems-manual__ac-pressure-zone-d-diagnosis). If not, go to next step.
5. See the pressures recorded during the A/C SYSTEM 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 5) 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 5) 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»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 4) Are the outlet temperatures within the specified ranges of the A/C Performance Test 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/manual-hvac-system/#hvac-systems-manual) 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»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. Add the specified amount of refrigerant oil to the accumulator. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__specifications). Install the accumulator. See ACCUMULATOR 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 A/C System Performance Chart. (Scheme 5) 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/manual-hvac-system/#hvac-systems-manual__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 «SYMPTOM DIAGNOSIS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__symptom-diagnosis) under TROUBLESHOOTING.

Scheme 5

A/C PRESSURE ZONE "B" DIAGNOSIS

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

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/manual-hvac-system/#hvac-systems-manual__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 4) The high-side pressure is below the specified pressure range of the A/C Performance Table. (Scheme 4) 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 4.
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 4) The high-side pressure is below the specified pressure range of the A/C Performance Table. (Scheme 4) 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/manual-hvac-system/#hvac-systems-manual__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 step 6.
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 A/C Performance Chart. (Scheme 5) Are the readings within the specified ranges found on the A/C Performance Chart? 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual__compressor) under REMOVAL & INSTALLATION. Replace the orifice tube. See «ORIFICE TUBE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. Replace the A/C compressor. See «COMPRESSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__compressor) under REMOVAL & INSTALLATION. Replace the accumulator. See «ACCUMULATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual__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 «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLESHOOTING.

A/C PRESSURE ZONE "C" DIAGNOSIS

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

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/manual-hvac-system/#hvac-systems-manual__ac-performance-test) under PERFORMANCE TESTS.
2. With the engine idling, turn on the A/C. Inspect for proper cooling fan operation. See appropriate ELECTRIC COOLING FANS article in ENGINE COOLING. 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/manual-hvac-system/#hvac-systems-manual) 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 Chart. (Scheme 5) 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/manual-hvac-system/#hvac-systems-manual__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 «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLESHOOTING.

A/C PRESSURE ZONE "D" DIAGNOSIS

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

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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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/manual-hvac-system/#hvac-systems-manual) 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 Chart. (Scheme 5) Are the readings within the specified ranges as shown on the A/C Performance Chart? If so, go to next step. If not, go to «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLESHOOTING.

SYMPTOM TESTS

SYMPTOM TEST DIRECTORY

TEST A: AIR DELIVERY IMPROPER

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Turn off the HVAC controls. Is the blower motor off? If so, go to next step. If not, go to «TEST C: BLOWER MOTOR ALWAYS ON»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-c-blower-motor-always-on) .
3. Place the blower motor switch in each speed position. Does the blower motor operate in any of the speed positions? If so, go to next step. If not, go to «TEST D: BLOWER MOTOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-d-blower-motor-inoperative) .
4. Does the blower motor operate in each speed position? If so, go to next step. If not, go to «TEST E: BLOWER MOTOR MALFUNCTIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-e-blower-motor-malfunctions) .
5. Place the blower motor switch in the maximum speed position. Place the bi-level switch in the On position. Place the recirculation switch in the recirculation and ambient air positions. Does the recirculation door move from the recirculation position to the ambient air position? If so, go to next step. If not, go to «TEST B: AIR RECIRCULATION MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-b-air-recirculation-malfunction) .
6. Place the blower motor switch in the maximum speed position. Place the mode switches in each mode position. Does the air flow from the proper air distribution outlet in each mode position? If so, check for intermittent condition. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING. If not, go to next step.
7. Inspect the air delivery system for the following conditions: A dirty passenger compartment air filter, if applicable. An obstruction to the air flow. Air leaks. Misaligned ducts. Did you find and correct the condition? If so, go to step 18 . If not, go to step 8 .
8. Inspect the mode door and the mode actuator for the following conditions: Misaligned mode actuator See «MODE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. Broken or binding linkages. A broken or binding mode door. An obstruction that prevents the mode door from operating within its full range of motion. Missing seals to the mode door. Misaligned seals to the mode door. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
9. Turn the ignition off. Disconnect the mode actuator. Turn ignition on. Probe the ignition 3 voltage circuit of the mode actuator with a test light that is connected to ground. Does the test light illuminate? If so, go to next step. If not, go to step 15 .
10. Check the low reference circuit of the mode actuator for an open or high resistance. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
11. Measure the voltage from the mode door control circuit of the mode actuator to ground. Place the mode controls in each mode position. Does the measured voltage change for each change in selected mode position? If so, go to step 13 . If not, go to next step.
12. Check the mode door control circuit of the mode actuator for an open, a high resistance, a short to ground, or a short to voltage. Did you find and correct the condition? If so, go to step 18 . If not, go to step. 14 .
13. Inspect for poor connections at the harness connector of the mode actuator. Did you find and correct the condition? If so, go to step 18 . If not, go to step 16 .
14. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 18 . If not, go to step 17 .
15. Repair the ignition 3 voltage circuit of the mode actuator. After repairs are complete, go to step 18 .
16. Replace the mode actuator. See «MODE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 18 .
17. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
18. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 7 .

TEST B: AIR RECIRCULATION MALFUNCTION

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Place the blower motor switch in the maximum speed position. Place the BI-LEVEL switch in the ON position. Place the RECIRCULATION switch in the RECIRCULATION position and ambient air positions. Does the recirculation door move from the recirculation position to the ambient air position? If so, check for intermittent condition. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING. If not, go to next step.
3. Turn the ignition off. Disconnect the recirculation actuator. Turn ignition on. Probe the ignition 3 voltage circuit of the recirculation actuator with a test light that is connected to ground. Does the test light illuminate? If so, go to next step. If not, go to step 10 .
4. Check the low reference circuit of the recirculation actuator for an open or high resistance. Did you find and correct the condition? If so, go to step 13 . If not, go to next step.
5. Measure the voltage from the recirculation door control circuit of the recirculation actuator to ground. Place the recirculation switch in the recirculation position and the ambient air position. Does the measured voltage change? If so, go to step 7 . If not, go to step 6 .
6. Check the recirculation door control circuit of the recirculation actuator for an open, a high resistance, a short to ground, or a short to voltage. Did you find and correct the condition? If so, go to step 13 . If not, go to step 9 .
7. Inspect the recirculation door and the recirculation actuator for the following conditions: A misaligned recirculation actuator. See «RECIRCULATION ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. Broken or binding linkages. A broken or binding recirculation door. An obstruction that prevents the recirculation door from operating within its full range of motion. Missing seals to the recirculation door. Misaligned seals to the recirculation door. Did you find and correct the condition? If so, go to step 13 . If not, go to next step.
8. Inspect for poor connections at the harness connector of the recirculation actuator. Did you find and correct the condition? If so, go to step 13 . If not, go to step 11 .
9. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 13 . If not, go to step 12 .
10. Repair the ignition 3 voltage circuit of the recirculation actuator. After repairs are complete, go to step 13 .
11. Replace the recirculation actuator. See «RECIRCULATION ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 13 .
12. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
13. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 3 .

TEST C: BLOWER MOTOR ALWAYS ON

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Turn off the HVAC controls. Is the blower motor off? If so, condition is intermittent. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING. If blower motor is not off, go to step 3 .
3. Install a scan tool With the scan tool, observe the Commanded Blower parameter in the Climate Control Panel data list. Does the scan tool indicate that the Commanded Blower parameter is near zero percent? If so, go to next step. If not, go to step 6 .
4. Disconnect the HVAC control module. Does the blower motor continue to operate? If so, go to next step. If not, go to step 6 .
5. Inspect for poor connections at the harness connector of the blower motor control processor. Did you find and correct the condition? If so, go to step 9 . If not, go to step 7 .
6. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 9 . If not, go to step 8 .
7. Replace the blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 9 .
8. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
9. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, 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 HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Place the blower motor switch in each speed position. Does the blower motor operate in any of the speed positions? If so, go to «TEST E: BLOWER MOTOR MALFUNCTIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-e-blower-motor-malfunctions) . If not, go to next step.
3. Install a scan tool. Place the blower motor switch in the maximum speed position. With the scan tool, observe the COMMANDED BLOWER parameter in the CLIMATE CONTROL PANEL DATA LIST. Does the scan tool indicate that the COMMANDED BLOWER parameter is near 100 percent? If so, go to next step. If not, go to step 12 .
4. Turn the ignition off. Disconnect the blower motor connector. Turn ignition on. Connect a test light between the blower motor supply voltage circuit and the blower motor control circuit. Place the blower motor switch in the minimum speed position. Does the test light illuminate? If so, go to step 10 . If not, go to next step.
5. Check the battery positive voltage circuit of the blower motor control processor for an open, a high resistance or a short to ground. Did you find and correct the condition? If so, go to step 16 . If not, go to next step.
6. Check the ground circuit of the blower motor control processor for an open or a high resistance. Did you find and correct the condition? If so, go to step 16 . If not, go to next step.
7. Measure the voltage from the blower motor speed control circuit at the HVAC control module to ground. With a scan tool, command the blower motor OFF and ON. Is the voltage near 5.0 volts OFF and 1.5 volts ON for each commanded state? If so, go to step 9 . If not, go to next step.
8. Turn the ignition off. Disconnect the HVAC control module. Turn ignition on. Measure the voltage from the blower motor speed control circuit of the HVAC control module to ground. Is the voltage near 5.0 volts? If so, go to step 12 . If not, go to next step.
9. Check the blower motor speed control circuit of the HVAC control module for an open, a short to ground or a short to voltage. Did you find and correct the condition? If so, go to step 16 . If not, go to step 11 .
10. Inspect for poor connections at the harness connector of the blower motor. Did you find and correct the condition? If so, go to step 16 . If not, go to step 13 .
11. Inspect for poor connections at the harness connector of the blower motor control processor. Did you find and correct the condition? If so, go to step 16 . If not, go to step 14 .
12. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 16 . If not, go to step 15 .
13. Replace the blower motor. See «BLOWER MOTOR (WITHOUT VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) or «BLOWER MOTOR (WITH VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 16 .
14. Replace the blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 16 .
15. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
16. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 2 .

TEST E: BLOWER MOTOR MALFUNCTIONS

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Place the blower motor switch in each speed position. Does the blower motor operate at the desired speed? If so, check for an intermittent condition. If not, go to step 3 .
3. Install a scan tool. With a scan tool, observe the COMMANDED BLOWER parameter in the CLIMATE CONTROL PANEL DATA LIST. Place the blower motor switch from the minimum speed position to the maximum speed position. Does scan tool indicate that the COMMANDED BLOWER parameter increases within 10-100 percent? If so, go to next step. If not, go to step 10 .
4. Turn the ignition off. Disconnect the blower motor connector. Turn ignition on. Connect a test light between the blower motor supply voltage circuit and the blower motor control circuit. Place the blower motor switch from the minimum speed position to the maximum speed position. Does the test light illuminate and increase intensity? If so, go to step 8 . If not, go to next step.
5. Check the battery positive voltage circuit and ground circuit of the blower motor control processor for high resistance. Did you find and correct the condition? If so, go to step 14 . If not, go to next step.
6. Measure the voltage from the blower motor speed control circuit of the HVAC control module and ground. Place the blower control from the minimum speed position to the maximum speed position. Does the voltage decrease between 4.75-1.5 volts? If so, go to step 9 . If not, go to next step.
7. Turn the ignition off. Disconnect the HVAC control module. Turn ignition on. Measure the voltage from the blower motor speed control circuit of the HVAC control module to ground. Is the voltage near 5.0 volts? If so, go to step 10 . If not, go to step 9 .
8. Inspect for poor connections at the harness connector of the blower motor. Did you find and correct the condition? If so, go to step 14 . If not, go to step 11 .
9. Inspect for poor connections at the harness connector of the blower motor control processor. Did you find and correct the condition? If so, go to step 14 . If not, go to step 12 .
10. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 14 . If not, go to step 13 .
11. Replace the blower motor. See «BLOWER MOTOR (WITHOUT VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) or «BLOWER MOTOR (WITH VENT TUBE)»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 14 .
12. Replace the blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 14 .
13. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
14. Operate the system in order to verify the repair. Did you correct the condition? If so, system in okay. If not, 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 HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start the engine. Place the blower motor switch in the OFF position. Place the bi-level switch in the OFF position. Does the A/C compressor operate? If so, go to next step. If not, condition is intermittent. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING.
3. With the scan tool, observe the A/C COMMANDED parameter in the PCM data list. Does the scan tool indicate the A/C RELAY COMMAND parameter is ON? If so, go to next step. If not, go to step 6 .
4. With the scan tool, observe the CONTROL HEAD DESIRED parameter in the Dash Integration Module (DIM) A/C Information List. Does the scan tool display A/C OFF? If so, go to next step. If not, go to step 11 .
5. With a scan tool, observe the A/C CLUTCH DESIRED parameter in the DIM A/C Information List. Does the scan tool display OFF? If so, go to step 13 . If not, go to step 12 .
6. Turn the ignition off. Disconnect the A/C compressor relay. Turn the ignition on. Does the A/C compressor clutch disengage? If so, go to next step. If not, go to step 8 .
7. Check the A/C compressor relay control circuit of the A/C compressor relay for a short to ground. Did you find and correct the condition? If so, go to step 19 . If not, go to step 10 .
8. Check the A/C compressor clutch supply voltage circuit for a short to voltage. Did you find and correct the condition? If so, go to step 19 . If not, go to next step.
9. Inspect for poor connections at the harness connector of the A/C compressor clutch. Did you find and correct the condition? If so, go to step 19 . If not, go to step 15 .
10. Inspect for poor connections at the A/C compressor relay. Did you find and correct the condition? If so, go to step 19 . If not, go to step 14 .
11. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 19 . If not, go to step 16 .
12. Inspect for poor connections at the Dash Integration Module (DIM). Did you find and correct the condition? If so, go to step 19 . If not, go to step 17 .
13. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If so, go to step 19 . If not, go to step 18 .
14. Replace the A/C compressor relay. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 19 .
15. Replace the A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step 19 .
16. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 19 .
17. Replace the DIM. See DASH INTEGRATION MODULE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 19 .
18. Replace the 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.
19. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 2 .

TEST G: COMPRESSOR CLUTCH DOES NOT ENGAGE

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Start the engine. Place the blower motor switch in the maximum speed position. Place the bi-level in the ON position. Place the air temperature switch in the coldest position. Does the A/C compressor operate? If so, condition is intermittent. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING. If not, go to next step.
3. 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, about 2 minutes. Turn the ignition off. Install the ACR 2000 Air Conditioning Service Center. Record the ambient air temperature at the vehicle. Record readings of the low and high-side static pressures. Compare the low and high-side pressure values with the allowable limits for the recorded ambient air temperature. (Scheme 4) Are the low and high-side pressure values within the allowable limits for the recorded ambient air temperature, and within 15 psi (103 kPa) of each other? If so, go to next step. If not, check for refrigerant leaks. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
4. Turn ignition on. With a scan tool, observe the A/C HIGH SIDE PRESSURE SENSOR parameter in the POWERTRAIN DATA LIST Compare the A/C HIGH SIDE PRESSURE on the scan tool to the High Side Pressure Value on the ACR 2000. Are the high-side pressure values with 15 psi (103 kPa) of each other? If so, go to next step. If not, go to step 24.
5. Is the HVAC control module inoperative? If so, go to step 19. If not, go to next step.
6. Start the engine. With a scan tool, observe the A/C RELAY COMMAND parameter in the POWERTRAIN DATA LIST. Place the air temperature switch in the coldest position. Place the BI-LEVEL switch in the ON position. Does the scan tool indicate that the A/C RELAY COMMAND parameter is ON? If so, go to step 13. If not, go to next step.
7. With a scan tool, observe the A/C CLUTCH parameter DESIRED in the DIM A/C Information list. Does the scan tool indicate that the DESIRED is ON? If so, go to next step. If not, go to step 9.
8. With a scan tool, observe the A/C CLUTCH ACTUAL parameter in the DIM A/C Information list. Does the scan tool indicate that the A/C CLUTCH ACTUAL parameter is ON? If so, go to step 13. If not, go to step 33.
9. With a scan tool, observe the DESIRED CONTROL HEAD parameter in the DIM A/C Information list. Does the scan tool indicate that the DESIRED CONTROL HEAD parameter is A/C ON? If so, go to next step. If not, go to step 12.
10. With a scan tool, observe the PRESSURE STATUS parameter in the DIM A/C Information list. Does the scan tool indicate that the PRESSURE STATUS parameter is okay? If so, go to next step. If not, condition is intermittent. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING.
11. With a scan tool, observe the TEMPERATURE STATUS parameter in the DIM A/C Information list. Does the scan tool indicate that the TEMPERATURE STATUS parameter is okay? If so, go to step 30. If not, check for an engine overheating condition.
12. With a scan tool, observe the CONTROL HEAD DESIRED parameter in the DIM A/C information list. Place the mode switch in the DEFROST position. Does the scan tool indicate that the CONTROL HEAD DESIRED parameter is A/C ON and A/C OFF with each command? If so, go to step 30. If not, go to step 32.
13. With a scan tool, command the A/C Relay ON and OFF in the PCM SCAN TOOL OUTPUT CONTROLS. Does the A/C compressor relay turn ON and OFF with each command? If so, go to step 17. If not, go to next step.
14. Turn the ignition off. Disconnect the A/C compressor relay. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. Turn ignition on. Probe the ignition voltage circuit of the A/C compressor relay with a test light to ground. Does the test light illuminate? If so, go to next step. If not, go to step 27.
15. Connect a test light between the control circuit and the coil side ignition 3 voltage circuit of the A/C compressor relay. With a scan tool, command the A/C Relay ON and OFF. Does the test light turn ON and OFF with each command? If so, go to step 29. If not, go to next step.
16. Does the test light remain illuminated with each command? If so, go to step 22. If not, go to step 21.
17. Turn the ignition off. Disconnect the A/C compressor relay. Probe the switch side positive voltage circuit of the A/C compressor relay with a test light to ground. Does the test light illuminate? If so, go to next step. If not, go to step 26.
18. Connect a 10-amp fused jumper wire between the A/C compressor relay switch side positive voltage circuit and the A/C compressor clutch supply voltage circuit. Turn ignition on. Does the A/C compressor clutch engage? If so, go to step 29. If not, go to step 23.
19. Check the ignition 3 voltage circuit of the HVAC control module for a short to ground, a high resistance, or an open. Did you find and correct the condition? If so, go to step 40. If not, go to next step.
20. Check the ground circuit of the HVAC control module for an open. Did you find and correct the condition? If so, go to step 40. If not, go to step 32.
21. Check the A/C compressor relay control circuit for an open. Did you find and correct the condition? If so, go to step 40. If not, go to step 32.
22. Check the A/C compressor relay control circuit for a short to ground. Did you find and correct the condition? If so, go to step 40. If not, go to step 33.
23. Check the A/C compressor clutch supply voltage circuit at the coil for a short to ground, a high resistance, or an open. Did you find and correct the condition? If so, go to step 40. If not, go to step 25.
24. Check the ground circuit of the A/C refrigerant pressure sensor for an open. Did you find and correct the condition? If so, go to step 40. If not, go to step 28.
25. Check the A/C compressor clutch ground circuit for a high resistance or an open. Did you find and correct the condition? If so, go to step 40. If not, go to step 31.
26. Repair the A/C compressor relay switch side voltage circuit. After repairs are complete, go to step 40.
27. Repair the A/C compressor relay coil side ignition voltage circuit. After repairs are complete, go to step 40.
28. Inspect the A/C refrigerant pressure sensor for poor connections. Did you find and correct the condition? If so, go to step 40. If not, go to step 35.
29. Inspect for poor connections at the A/C compressor relay. Did you find and correct the condition? If so, go to step 40. If not, go to step 36.
30. Inspect the DIM for poor connections. Did you find and correct the condition? If so, go to step 40. If not, go to step 34.
31. Inspect the A/C compressor clutch for poor connections. Did you find and correct the condition? If so, go to step 40. If not, go to step 37.
32. Inspect the HVAC control module for poor connections. Did you find and correct the condition? If so, go to step 40. If not, go to step 38.
33. Inspect the PCM for poor connections. Did you find and correct the condition? If so, go to step 40. If not, go to step 39.
34. Replace the DIM. See appropriate in BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to step 40.
35. Replace the A/C high-pressure sensor. See «REFRIGERANT PRESSURE SENSOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 40.
36. Replace the A/C compressor relay. See «COMPRESSOR RELAY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 40.
37. Replace the A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step 40.
38. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 40.
39. Replace the 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.
40. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 3.

TEST H: DEFROSTING INSUFFICIENT

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

1. Start the engine. Select the DEFROST mode. Select the maximum blower speed. Does sufficient air flow from the defroster outlets? If so, go to step 2 . If not, go to step 9 .
2. Measure the engine operating temperature. Does engine reach a normal operating temperature? If so, go to next step. If not, go to step 4 .
3. 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 5 . If not, go to step 11 .
4. Repair the low engine temperature concern. After repairs are complete, go to step 13 .
5. Check the operation of the A/C compressor clutch. Does the A/C compressor clutch engage? If so, go to step 7 . If not, go to next step.
6. Repair the A/C compressor clutch. See «TEST G: COMPRESSOR CLUTCH DOES NOT ENGAGE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-g-compressor-clutch-does-not) . After repairs are complete, go to step 13 .
7. Perform the A/C SYSTEM PERFORMANCE TEST. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__ac-performance-test) under PERFORMANCE TESTS. Is the A/C system operating within the specifications? If so, go to next step. If not, go to step 10 .
8. Inspect for correct operation of the recirculation door. Is the recirculation door operating correctly? If so, go to step 13 . If not, go to step 12 .
9. Repair the air delivery concern. See «TEST A: AIR DELIVERY IMPROPER»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-a-air-delivery-improper) . After repairs are complete, go to step 13 .
10. Repair the A/C performance concern. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__ac-performance-test) under PERFORMANCE TESTS. After repairs are complete, go to step 13 .
11. Repair the heating concern. See «HEATER PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__heater-performance-test) under PERFORMANCE TESTS. After repairs are complete, go to step 13 .
12. Repair the recirculation door concern. See «TEST B: AIR RECIRCULATION MALFUNCTION»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-b-air-recirculation-malfunction) . After repairs are complete, go to next step.
13. Operate the system in order to verify the repair. Does the system operate correctly? If so, system is okay, If not, go to step 1 .

TEST I: TOO COLD IN VEHICLE

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Place the blower control in each speed position. Does the blower motor operate in any of the speed positions? If so, go to next step. If not, go to «TEST D: BLOWER MOTOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-d-blower-motor-inoperative) .
3. Does the blower motor operate in each speed position? If so, go to next step. If not, go to «TEST E: BLOWER MOTOR MALFUNCTIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-e-blower-motor-malfunctions) .
4. Start the engine. Turn off the HVAC controls. Does the A/C compressor clutch engage? If so, go to «TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-f-compressor-clutch-does-not) . If not, go to next step.
5. Inspect the cooling system for the following conditions: A low coolant level. A loose or worn accessory drive belt. A leaking radiator hose or heater hose. A kinked radiator hose or heater hose. A missing radiator cap pressure seal. A leaking radiator cap. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
6. Perform the Heating Performance Diagnostic. See «HEATER PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__heater-performance-test) . Did you find and correct the condition? If yes, go to step 18 . If not, go to step 7 .
7. Turn ignition on. Observe the drive shaft of the air temperature actuator. Place the air temperature switch from the coldest position to the warmest position. Does the air temperature actuator drive shaft rotate at all? If so, go to step 8 . If not, go to step 9 .
8. Inspect the air temperature door and the air temperature actuator for the following conditions: Misaligned air temperature actuator. Broken or binding linkages. Broken or binding air temperature door. An obstruction that prevents the air temperature door from operating within its full range of motion. Missing seals to the air temperature door. Misaligned seals to the air temperature door. Did you find and correct the condition? If so, go to step 18 . If not, check for intermittent condition. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING.
9. Check the air temperature actuator ignition 3 voltage circuit of for an open or a high resistance. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
10. Check the air temperature actuator low reference circuit of for an open. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
11. Check the air temperature door control circuit for an open, a high resistance, a short to ground, or a short to voltage. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
12. Turn ignition on. Measure the voltage from the air temperature door control circuit to ground. Place the air temperature switch from the coldest position to the warmest position. Is the voltage between zero volts (cold), and 12 volts (hot) with a smooth transition between cold and hot? If so, go to next step. If not, go to step 15 .
13. Inspect the air temperature actuator for poor connections. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
14. Inspect the air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation. Did you find and correct the condition? If so, go to step 18 . If not, go to step 16 .
15. Inspect the HVAC control module for poor connections. Did you find and correct the condition? If so, go to step 18 . If not, go to step 17 .
16. Replace the air temperature actuator. See «AIR TEMPERATURE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 18 .
17. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
18. Operate the system in order to verify the repair. Did you correct the condition? If so, system in okay. If not, go to step 2 .

TEST J: TOO HOT IN VEHICLE

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

1. Did you perform the HVAC DIAGNOSTIC SYSTEM CHECK? If so, go to next step. If not, go to «DIAGNOSTIC SYSTEM CHECK»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__diagnostic-system-check) under SELF-DIAGNOSTIC SYSTEM.
2. Turn ignition on. Place the blower motor switch in each speed position. Does the blower motor operate in any of the speed positions? If so, go to next step. If not, go to «TEST D: BLOWER MOTOR INOPERATIVE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-d-blower-motor-inoperative) .
3. Does the blower motor operate in each speed position? If so, go to next step. If not, go to «TEST E: BLOWER MOTOR MALFUNCTIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-e-blower-motor-malfunctions) .
4. When the A/C is on, does the customer concern occur? If so, go to next step. If not, go to step 7 .
5. Start the engine. Place the blower motor switch in the maximum speed position. Place the mode switch in the VENT position. Place the A/C request switch in the MAX position. Place temperature switch in the coldest position. Does the A/C compressor operate? If so, go to next step. If not, go to «TEST G: COMPRESSOR CLUTCH DOES NOT ENGAGE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__test-g-compressor-clutch-does-not) .
6. Perform the refrigerant system performance test. See «A/C PERFORMANCE TEST»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__ac-performance-test) under PERFORMANCE TESTS. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
7. Observe the air temperature actuator drive shaft. Place the air temperature switch from the coldest position to the warmest position. Does the drive shaft of the air temperature actuator rotate? If so, go to next step. If not, go to step 9 .
8. Inspect the air temperature door and the air temperature actuator for the following conditions: Misaligned air temperature actuator. Broken or binding linkages. Broken or binding air temperature door. An obstruction that prevents the air temperature door from operating within its full range of motion. Missing seals to the air temperature door. Misaligned seals to the air temperature door. Did you find and correct the condition? If so, go to step 18 . If not, condition is intermittent. See «INTERMITTENTS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__intermittents) under TROUBLE SHOOTING.
9. Check the air temperature actuator ignition circuit of for an open or a high resistance. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
10. Check the air temperature actuator low reference circuit of for an open. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
11. Check the air temperature door control circuit for an open, a high resistance, a short to ground, or a short to voltage. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
12. Turn ignition on. Measure the voltage from the air temperature door control circuit of the air temperature actuator to ground. Place the air temperature switch from the coldest position to the warmest position. Is the voltage between zero volts (cold) and 12 volts (hot) with a smooth transition between cold and hot? If so, go to next step. If not, go to step 15 .
13. Inspect for poor connections at the harness connector of the air temperature actuator. Did you find and correct the condition? If so, go to step 18 . If not, go to next step.
14. Inspect the air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation. Did you find and correct the condition? If so, go to step 18 . If not, go to step 16 .
15. Inspect for poor connections at the harness connector of the HVAC control module. Did you find and correct the condition? If so, go to step 18 . If not, go to step 17 .
16. Replace the air temperature actuator. See «AIR TEMPERATURE ACTUATOR»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to step 18 .
17. Replace the HVAC control module. See «HVAC CONTROL MODULE»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual) under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
18. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step 2 .

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 6) Disconnect the evaporator hose from the accumulator cover. (Scheme 7)
3. Remove the accumulator cover. (Scheme 8) Remove the A/C compressor hose nut from the accumulator. (Scheme 9)
4. Disconnect the A/C compressor hose from the accumulator. Remove the evaporator hose nut from the accumulator. (Scheme 10)
5. Remove the evaporator hose from the accumulator. Remove the accumulator from the housing.

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Installation

1. Add the proper amount of refrigerant oil to the accumulator. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__specifications). Install the accumulator into the housing. (Scheme 11)
2. Install NEW sealing washers. Connect the evaporator hose to the accumulator. (Scheme 10)
3. Install and tighten the evaporator hose nut. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Connect the A/C compressor hose to the accumulator. (Scheme 9)
4. Install the A/C compressor hose nut. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the accumulator cover. (Scheme 8)
5. Connect the evaporator hose into the retainer. (Scheme 7) Install the positive battery cable and nut to the underhood fuse block.
6. Connect the negative battery cable. (Scheme 6) 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 11

1. Remove the I/P compartment. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Disconnect the electrical connector from the air temperature actuator.
2. Remove the air temperature actuator retaining screws. (Scheme 12) Remove the air temperature actuator. (Scheme 13)

Scheme 12

Scheme 13

1. Install the air temperature actuator. (Scheme 13) Install the air temperature retaining screws. (Scheme 12) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Connect the electrical connector to the air temperature actuator.
2. 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/manual-hvac-system/#hvac-systems-manual__calibrating-actuators) under ADJUSTMENTS.

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 two rear DIM bracket screws. (Scheme 14)
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 15)
4. Lower the blower motor and rotate counterclockwise to remove from the vehicle.

Scheme 14

Scheme 15

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/manual-hvac-system/#hvac-systems-manual__torque-specifications). Connect the electrical connector to the blower motor. (Scheme 15)
2. Reposition the DIM bracket to its original position. Install the two rear DIM bracket screws. (Scheme 14) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 16)
2. Remove the blower motor screws. Remove the blower motor from the housing. (Scheme 17)

Scheme 16

Scheme 17

1. Install the blower motor into the housing. Install the blower motor screws. (Scheme 17) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Install the blower ventilation tube to the module. Connect the blower motor electrical connector. (Scheme 16) 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 18) Remove the blower control module retaining screw. Remove the blower control module.

Scheme 18

1. Install the blower control module. Install the retaining screw. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Connect the electrical connector. (Scheme 18) Install the DIM bracket screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
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/manual-hvac-system/#hvac-systems-manual__calibrating-actuators) 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 19)
4. Disconnect the electrical connector from the A/C pressure sensor. Remove the retaining bolt from the wiring harness bracket. (Scheme 20)
5. Remove the A/C compressor hose nut. Remove the A/C compressor hose from the compressor. (Scheme 21)
6. Remove the front compressor mounting nuts. Remove the rear compressor mounting bolt. (Scheme 22) 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 19

Scheme 20

Scheme 21

Scheme 22

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/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Install the rear bolt to the compressor. Tighten to specification. Install the A/C compressor hose to the compressor. (Scheme 21)
3. Install the A/C compressor hose nut. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Connect the electrical connector to the compressor. (Scheme 19)
4. Connect the electrical connector to the A/C pressure sensor. Install the retaining bolt to the wiring harness bracket. (Scheme 20) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 19) Remove the A/C compressor hose nut at the compressor. (Scheme 21) 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 23)
4. Remove the A/C compressor hose nut at the accumulator. (Scheme 10) 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 23

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 21) Install the A/C compressor hose nut. Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Connect the electrical connector to the A/C pressure switch. (Scheme 19) Connect the A/C compressor hose to the condenser. Install the A/C compressor hose nut. (Scheme 23) Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
3. Install the A/C compressor hose and nut to the accumulator. (Scheme 9) Tighten to specified torque. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 24)

Install the A/C compressor relay to the electrical center. (Scheme 24) Install the electrical center cover.

Scheme 24

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 headlamp and bumper fascia mounting panel and position out of the way. Remove the upper radiator seal. (Scheme 25)
3. Remove the upper radiator mounting brackets. (Scheme 26) Disconnect the compressor hose from the condenser. (Scheme 23)
4. Remove the front headlamps. Disconnect the evaporator hose from the condenser. (Scheme 27)
5. Remove the fasteners from the left and right sides of the headlamp and bumper fascia mounting panel. (Scheme 28) Lift the headlamp and bumper fascia mounting panel and pull forward in car to obtain access to the condenser mounting bolts.
6. Remove the two 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 two A/C condenser seals. (Scheme 29) Lift the condenser up and remove from the vehicle.

Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

1. Add the proper amount of refrigerant oil to the NEW condenser. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the NEW A/C condenser seals. (Scheme 29)
4. Reposition the headlamp and bumper fascia mounting panel and install the fasteners. (Scheme 28) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install NEW seal washers.
5. Install the evaporator hose and nut to the condenser. (Scheme 27) Install the compressor hose and nut to the condenser. (Scheme 23) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
6. Install the upper radiator mounting brackets and bolts. (Scheme 26) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the upper radiator seal. (Scheme 25)
7. Install the front fascia to tie bar support brackets and bolts. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the front headlamps.
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/manual-hvac-system/#hvac-systems-manual). Remove the seal from around the heater core and the evaporator tubes. (Scheme 30)
2. Remove the upper HVAC evaporator case screws. Separate the HVAC evaporator case halves. Remove the evaporator core. (Scheme 31)

Scheme 30

Scheme 31

1. Add the proper amount of refrigerant oil to the evaporator. See «SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__specifications). Install the evaporator core into the module housing. (Scheme 31)
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/manual-hvac-system/#hvac-systems-manual__torque-specifications).
3. Install the seal over the heater core and the evaporator pipes. (Scheme 30) Install the HVAC assembly. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual).

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 32) 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 33)
5. Remove the heater core heat shield screws. Remove the heater core heat shield. Remove the heater core cover screws. (Scheme 34)
6. Remove the heater core cover. Remove the retaining screw and strap from the heater core. Remove the heater core.

Scheme 32

Scheme 33

Scheme 34

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/manual-hvac-system/#hvac-systems-manual__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/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the heater core heat shield.
3. Install the heater core heat shield screws. (Scheme 34) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the air distributor duct.
4. Install the air distributor duct left side screw. (Scheme 33) Ensure the right tab is seated properly. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 32) 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 32) 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 35)
3. Remove the air distributor duct screws. (Scheme 36) Remove the air distributor duct.
4. Remove the heater core heat shield screws. (Scheme 34) 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 35

Scheme 36

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/manual-hvac-system/#hvac-systems-manual__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 34) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
3. Install the air distributor duct. Install the air distributor duct left side screw. (Scheme 36) Ensure the right side tab is seated properly. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
4. Install the auxiliary air distribution duct adapter. (Scheme 35) 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 32) Install the fuel injector sight shield. Fill the cooling system.

Remove the right I/P accessory trim plate. Pinch the tabs on the control module and pull rearward on the HVAC control module to remove from the I/P. (Scheme 37)

Scheme 37

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 37) 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 38) Disconnect the evaporator hose connection at the evaporator.
3. Remove the heater hoses from the heater core using the hose clamp pliers. (Scheme 39) 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 40)
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 18) Remove the HVAC module retaining nuts. Remove the HVAC module. (Scheme 41)

Scheme 38

Scheme 39

Scheme 40

Scheme 41

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/manual-hvac-system/#hvac-systems-manual__torque-specifications). (Scheme 41)
2. Connect the blower control module connection. Connect the I/P harness to HVAC module connector. (Scheme 18) Install the defroster duct.
3. Install the defroster duct module mounting screws. Install the defroster duct mounting nut to the front of dash. (Scheme 40) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the air distributor duct.
4. Install the air distributor duct screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 39) Install NEW seal washers to the fitting.
6. Connect the evaporator hose connection to the evaporator. (Scheme 38) Install the evaporator hose nut. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__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 left sound insulator. Remove the knee bolster.
2. Remove the Instrument Panel Module (IPM). See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. Disconnect the electrical connector from the mode actuator.
3. Remove the mode actuator retaining screws. (Scheme 42) Remove the mode actuator.

Scheme 42

1. Align the mode door levers with the cam slots. Install the mode actuator. Install the mode actuator retaining screws. (Scheme 42) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Connect the electrical connector to the mode actuator. Install the IPM. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Install the knee bolster. Install the left side sound insulator. Recalibrate the actuator. See «CALIBRATING ACTUATORS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__calibrating-actuators).

1. Remove the HVAC Module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual). 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 43)
4. Remove the actuator cam from the door. (Scheme 44) Remove the mode door. (Scheme 45)

Scheme 43

Scheme 44

Scheme 45

1. Install the mode door. Install the actuator cam to the mode door. (Scheme 45)
2. Close the module case. (Scheme 43) Install the module case screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the mode actuator and bracket.
3. Install the mode actuator screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the left temperature actuator.
4. Install the actuator screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the HVAC module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual).

1. Remove the HVAC Module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual). 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 44)
4. Remove the spring from the upper mode door. (Scheme 46) Remove the upper mode door.

Scheme 46

1. Install the upper mode door. Attach the spring to the upper mode door. (Scheme 46)
2. Install the actuator cam to the mode door. (Scheme 44) 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/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the left temperature actuator.
4. Install the actuator screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). 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 7)
2. Separate the A/C evaporator hose at the orifice tube location. (Scheme 47) Remove the orifice tube from the line. (Scheme 48)

Scheme 47

Scheme 48

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 48) Connect the A/C evaporator tube and tighten. (Scheme 47)
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 49) To install, reverse removal procedure.

Scheme 49

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. Remove the rear two DIM module bracket screws. (Scheme 14)
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 13)

1. Install the recirculation actuator. (Scheme 13) Install the recirculation actuator retaining screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Connect the electrical connector to the recirculation actuator. Position the DIM module bracket to its original position. (Scheme 14) Install the rear two DIM module bracket retaining screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
3. Install the DIM module into the bracket. Install the right sound insulator. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
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/manual-hvac-system/#hvac-systems-manual__calibrating-actuators).

1. Remove the HVAC Module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual). Remove the recirculation housing screws. (Scheme 50)
2. Remove the recirculation housing. Remove the recirculation door from the housing.

Scheme 50

1. Install the recirculation door into the housing. Install the recirculation housing. (Scheme 50)
2. Install the recirculation housing screws. Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications). Install the HVAC module. See «HVAC MODULE ASSEMBLY»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual).

1. Disconnect the electrical connector from the A/C refrigerant pressure sensor. (Scheme 19)
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/manual-hvac-system/#hvac-systems-manual__torque-specifications). Connect the electrical connector to the A/C refrigerant pressure sensor. (Scheme 19)

Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. (Scheme 51)

Scheme 51

1. Lubricate the O-ring using 525 refrigerant oil. Install the service fitting to the line. (Scheme 51) Tighten to specification. See «TORQUE SPECIFICATIONS»(/buick/lesabre/viii-2000-2005/remont/manual-hvac-system/#hvac-systems-manual__torque-specifications).
2. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 52

Scheme 53

Scheme 54

Scheme 55

Scheme 56

Scheme 57

Scheme 58

WIRING DIAGRAMS

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

See also:
• COMPUTERIZED ENGINE CONTROLS
• SELF DIAGNOSTIC SYSTEM
• SYMPTOM DIAGNOSIS
• PRELIMINARY INSPECTION
• WIRING DIAGRAMS
• SYMPTOM TESTS
• A/C PRESSURE ZONE "A" DIAGNOSIS
• A/C PRESSURE ZONE "B" DIAGNOSIS
• A/C PRESSURE ZONE "C" DIAGNOSIS
• A/C PRESSURE ZONE "D" DIAGNOSIS
• TEST I: TOO COLD IN VEHICLE
• REMOVAL & INSTALLATION
• DIAGNOSTIC SYSTEM CHECK
• HEATER CORE (WITHOUT CONSOLE)
• HEATER CORE (WITH CONSOLE)
• CLEARING DIAGNOSTIC TROUBLE CODES
• P0530
• P1536
• P1540
• P1546
• INTERMITTENTS
• TEST F: COMPRESSOR CLUTCH DOES NOT DISENGAGE
• DIAGNOSTIC AIDS
• CONDITIONS FOR RUNNING DTC
• A/C PERFORMANCE TEST
• TEST J: TOO HOT IN VEHICLE
• SPECIFICATIONS
• COMPRESSOR
• A
• B
• C
• D
• E
• G
• H
• HEATER PERFORMANCE TEST
• TORQUE SPECIFICATIONS
• CALIBRATING ACTUATORS