HVAC System - Automatic - Aurora: Other Oldsmobile Aurora II

A/C-HEATER CONTROL HEAD

The A/C-heater control head displays temperature settings and readings on a Vacuum Fluorescent (VF) display panel. The control head contains buttons to select fresh outside air, manually select temperature control and A/C compressor on and off operation. A mode control knob controls manual operation of different modes and FAN control knob regulates blower speeds. Function of both control knobs can be put in automatic operation by depressing them. (Scheme 8)

Scheme 8

BLOWER CONTROL MODULE

Blower speed is controlled by a blower control module located behind right side of dash, near blower motor. Blower control module processes a 5-volt Pulse Width Modulated (PWM) voltage signal from Instrument Panel Control Module (IPM) which receives information from A/C-heater control head. The voltage is then amplified by the blower control module to provide variable blower speed.

DASHBOARD INTEGRATION MODULE

The Dashboard Integration Module (DIM), reads inputs from A/C refrigerant low temperature sensor and temperature control switch on steering wheel. The dash integration module controls the dual zone orifice solenoid and A/C compressor clutch. The module is located at right side kick panel.

INSTRUMENT PANEL MODULE

The instrument panel module receives signals from the A/C-heater control head, sun load sensors, ambient temperature sensor, in-vehicle temperature sensor, blower control module, Powertrain Control Module (PCM), upper and lower left/right air temperature sensors and temperature mode actuators. A microprocessor in the module processes the signals and then sends commands to the system components to control A/C compressor clutch operation, air intake location, air discharge location, air discharge temperature and blower speed. Instrument panel module is located under left side of instrument panel.

Ambient Temperature Sensor

Sensor is located on center of lower radiator support. The ambient air temperature sensor provides the IPM with temperature of the air outside the vehicle. The temperature is displayed on the HVAC control head. As the air temperature increases, resistance decreases and the remaining voltage is sent back to the IPM providing input from the sensor.

In-Vehicle Temperature Sensor

Sensor is located behind center of dash, right of steering column. A dedicated air hose draws in-vehicle air through aspirator past a sensor to accurately provide temperature readings from inside vehicle. As the air temperature increases, resistance decreases and the remaining voltage is sent back to the IPM providing input from the sensor.

Sunload Sensors

The sunload sensor assembly houses both the driver's and passenger's side sensors, and is located on each side of defrost grille. The sensor assembly provides the Instrument Panel Module (IPM) with the amount of sun light entering the vehicle through the driver's and passenger's side of windshield. A reference signal is sent from the IPM to the sunload sensor. A variable photo-diode resistor inside the sensor varies the voltage. The varied voltage provides a separate driver and passenger signal to the IPM. The sunload sensor also provides an average reading for the twilight sentinel feature. The remaining voltage is sent back to the IPM, providing input from the sensor.

Upper & Lower Air Temperature Sensors

Both upper and lower air temperature sensors provide the IPM with the temperature of the air exiting the A/C ducts located at both right and left A/C ducts. A reference signal is sent from the IPM to both the left and right air temperature sensors. A thermistor inside the sensor varies the voltage. Remaining voltage is sent back to the IPM, providing input from the sensor.

STEERING WHEEL CONTROLS

Temperature and fan speed are adjustable from control switches on the steering wheel. When either function is selected, AUTO mode is disabled and manual control is activated. Power to the steering wheel controls is delivered from the Dash Integration Module (DIM), through the instrument panel fuse box and air bag clockspring. When the temperature or fan control switch is moved up or down, voltage is sent through a series of resistors. Varied voltage is sent through air bag clockspring to the dash integration module. Once the signal is received at the DIM, information is sent to the Instrument Panel Module (IPM) where the air temperature door actuator or fan speed is adjusted.

Off Mode

In off mode, blower motor and A/C compressor will not run. Temperature control circuit is still activated so A/C-heater programmer can operate air mix door and attempt to match in-vehicle and selected temperatures. Since compressor is not running, system can be warmed but not cooled. If passenger-side temperature control switch has been turned on, it can be turned off by pressing the mode control knob. Depressing the mode control knob a second time will turn off entire Heater Ventilation Air Conditioning (HVAC) system.

After Blow Mode

The Instrument Panel Module (IPM) can be programmed to operate the blower motor for 4 minutes after the vehicle engine has been shut off. This blower operation dries evaporator core which reduces the amount of microbial growth and undesirable odors. The after blow mode must be enabled by a scan tool. In order for the IPM to operate the blower motor in after blow mode, ambient air temperature must be 70°F (21°C) or more. A/C compressor must have been operating for more than 3 minutes, the engine has been turned off for 45 minutes and system voltage must be 12 volts or more. See AFTER BLOW ENABLE PROCEDURE under PROGRAMMING.

Auto Mode

The automatic HVAC system will warm up/cool down and maintain the interior temperature of the vehicle by controlling the A/C compressor clutch, blower motor, air temperature, mode and recirculation actuators to achieve the selected temperature. Both the blower and mode switches must be in the auto position for fully automatic operation. Blower speeds will change automatically based on inputs to the Instrument Panel Module (IPM). The IPM will always come back to the last settings after an ignition cycle or, if equipped, to the last settings of the driver by pressing the unlock button on the remote keyless entry fob and placing the ignition in run.

When the engine is first started, the mode actuator will move to the floor mode and run the blower at low speed for 10 seconds to purge accumulated moisture in the HVAC assembly to prevent window fogging. Purge mode can be by-passed if any manual modes are selected during the 10 second purge.

In cold temperatures, the HVAC system will provide heat in the most efficient manner. When starting the engine in cold weather, the blower operates for 3 minutes and the IPM directs mode outlets to the windshield. In order to prevent windshield fogging, as coolant temperature increases, blower speed is increased. The purge can be by-passed if any manual modes are selected. To warm the interior quickly, maximum heat mode is used when the blower is set at maximum speed, air temperature door actuator is in floor mode, temperature is full hot and ambient air is being drawn in. Once the desired temperature is reached, temperature, mode and blower motor will be adjusted automatically by the IPM.

In warm temperatures, the automatic HVAC system will provide A/C in the most efficient manner. On vehicle start up, the IPM moves the mode door toward the floor and runs the blower for 3 seconds to avoid blowing hot, moist air on the driver. The IPM will monitor for conditions that indicate the possible presence of moisture in the HVAC module. This purge mode can be by-passed if any manual modes are selected. To cool the interior quickly, maximum cool mode is used when the blower is at maximum speed, air temperature door actuator is in full cold and the recirculation actuator is drawing air from inside the vehicle. The vehicle operator can select the extreme cool setting, but the system will not cool the vehicle any faster. Once the desired temperature is reached, temperature, mode and blower motor will be adjusted automatically by the IPM.

Front Defrost

The front defrost mode is the only setting that is not controlled by the automatic HVAC system. When defrost is selected, the A/C compressor is turned on. The blower motor will run and air will be directed toward the windshield, regardless of coolant temperature. The rear window defogger has no effect on the HVAC system at all.

Recirculation Mode

When mode control switch is depressed, a signal is sent from the HVAC control head to the Instrument Panel Module (IPM), and to the recirculation actuator. The recirculation actuator moves into the recirculation mode when the IPM receives the signal. This circulates air from inside the vehicle instead of outside. Power is supplied when ignition is on. Ground is provided by the IPM. The recirculation actuator is equipped with feedback potentiometers. When the actuator receives 5 volts, the actuator moves in one direction. When the actuator receives zero volts it moves in the opposite direction. When the actuator receives 2.5 volts, actuator rotation stops. A reference signal is sent out from the IPM, to the recirculation actuator.

When a manual recirculation setting is selected, a separate reference signal is sent from the IPM. Reference voltage is used by the IPM to determine the position of the recirculation actuators. Recirculation mode can be used for both automatic and manual operation. Recirculation mode is not available is when front defrost or vent is selected. Recirculation button will flash when recirculation mode is not available. When manually selected, recirculation will stay on until vent is selected or the recirculation mode has been on for about 10 minutes. Recirculation will come on automatically when maximum cooling is required in the automatic mode. When the HVAC system is off, pressing the recirculation switch will set the blower, mode and A/C compressor clutch in automatic mode.

Vent Mode

When the vent button is depressed, outside air is brought into the vehicle and the A/C compressor clutch is turned off. The vent button will not effect the HVAC system when the front defrost mode is selected. If the vent button is pressed while system is in front defrost mode, the vent button will flash 3 times to remind the driver that vent mode is not available. When the HVAC system is off, pressing the vent switch will put the HVAC system in automatic mode.

Dual Zone Control Switch

Passenger temperature control switch is provided to allow selection of air discharge temperatures on right side of vehicle. Temperatures can be set 8°F (4°C) cooler or warmer than the driver's setting. The switch has LEDs which will illuminate and inform the passenger of the setting. To operate in dual zone, the passenger moves the switch to the desired setting. Temperature offset will be allowed as long as the set temperature is not in maximum hot, or maximum cold settings.

Passenger-side temperature control switch can be turned off by turning the mode control knob fully counterclockwise. The entire HVAC system will turn off if mode control knob is turned fully counterclockwise a second time. Increased sun load on one side of the vehicle may cause the air temperatures to be different, even if the HVAC system is not operating in a dual zone mode. A 5-volt signal is sent to the passenger-side temperature control switch assembly through the passenger temperature control switch voltage supply circuit.

When a temperature switch is operated, voltage is sent through a series of in-line resistors, which varies the voltage. Driver door module communicates this message to passenger door module on 4 different passenger temperature signal circuits. When the temperature offset request is made to the passenger door module, the signal is sent to the driver door module. The driver door module is connected to the passenger door module through the power door serial data circuit.

AFTER BLOW ENABLE PROCEDURE

Connect a scan tool. Turn ignition on. Select INSTRUMENT PANEL MODULE, select SPECIAL FUNCTIONS and select AFTERBLOW. Select YES to enable after blow. Disconnect scan tool.

A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in INSTRUMENT PANEL MODULE SPECIAL FUNCTIONS. Observe current DTC list in Instrument Panel Module (IPM). If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If scan tool did not display any DTCs, go to next step.
3. Inspect for a low battery condition or poor battery connections. Recharge or replace battery, or repair connections if necessary. If battery and connections are okay, go to next step.
4. Inspect trim fit near A/C and heater control, steering wheel controls and personalization control for interference, causing a switch to stick. Correct any problem found. If no problem was found, go to next step.
5. Verify customer is using correct key to enable personalization process. Verify customer is not accidently activating steering wheel or passenger HVAC controls. If no problem was found, check for loose wires and/or poor connections at HVAC control head. If wire and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.
6. Turn engine off. Connect scan tool. Cover sunload sensor. Start engine. Select 75°F (24°C) temperature. Place air temperature switch in neutral position. Using scan tool, observe RIGHT and LEFT SUNLOAD SENSOR DATA parameters in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates that RIGHT and LEFT SUNLOAD SENSOR DATA parameters are 224 counts or more, go to next step. If scan tool indicates that RIGHT and LEFT SUNLOAD SENSOR parameters are less than 224 counts, check for loose wires and/or poor connections at sunload harness connector. If wires and connectors are okay, replace sunload sensor. See «SUN LOAD SENSOR»(ref-91547-S18469500342001042400000) under REMOVAL & INSTALLATION.
7. Uncover sunload sensor. Direct a light source at right and left side of sensor assembly. If count changes are similar from one sunload sensor to the other, go to next step. If count changes are not similar from one sunload sensor to the other, check for loose wires and poor connectors at sunload sensor. If wires and connections are okay, replace sunload sensor.
8. Start engine. Fully open all panel outlets. Adjust temperature setting to 75°F (24°C) position. Place mode switch in panel (upper) position. Set blower speed so 2 bars illuminate on fan speed indicator. Place air temperature switch in neutral position. Inspect airflow through inside air temperature sensor by placing a 2" (5 cm) square piece of paper over sensor air inlet. If paper stays in place, go to next step. If suction does not hold paper in place, inspect for blocked or disconnected aspiration hose. Repair as necessary.
9. Inspect upper and lower, right and left, air temperature sensors for proper installation. Correct any problems found. If no problems are found, check for loose wires and/or poor connections at upper and lower, left and right air temperature sensor harness connectors. Repair any problems found. If no problems were found, go to next step.
10. Check continuity in upper and lower, right and left air temperature sensors. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table. If any sensors are not within specifications, replace faulty air temperature sensor. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION. If all sensors are within listed resistance values, check for loose wires and/or poor connections to ambient air temperature sensor. If all wiring and connectors are okay, test ambient air temperature sensor resistance. If resistance is okay, go to next step. If resistance is not okay, replace ambient air temperature sensor. See «AMBIENT AIR TEMPERATURE SENSOR»(ref-91547-S37932928542001042400000) under REMOVAL & INSTALLATION.
11. Inspect inside air temperature sensor for loose wires and/or poor connections. Repair any problems found. If wires and connections are okay, test inside air temperature sensor resistance. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table. If inside air temperature resistance is not okay, replace inside air temperature sensor. See «INSIDE AIR TEMPERATURE SENSOR»(ref-91547-S11790020442001032600000) under REMOVAL & INSTALLATION. SENSOR RESISTANCE Ambient Temp. - °F (°C) Outside Temp. Air Resistor - K/Ohms Inside Air Temp. Resistor - K/Ohms 14 (-10) 5.27-5.98 15.42-16.89 23 (-5) 4.03-4.52 11.76-12.80 32 (0) 3.11-3.44 9.03-9.75 41 (5) 2.43-2.66 7.00-7.53 50 (10) 1.91-2.07 5.47-5.85 59 (15) 1.51-1.62 4.31-4.58 68 (20) 1.21-1.28 3.41-3.61 77 (25) 0.97-1.02 2.72-2.86 86 (30) 0.78-0.82 2.17-2.29 95 (35) 0.63-0.67 1.74-1.85 104 (40) 0.51-0.55 1.41-1.50

Scheme 9

Scheme 10

Scheme 11

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Turn ignition on. Turn off all HVAC controls. If blower motor is off, go to next step. If blower motor is on, see «BLOWER MOTOR ALWAYS ON»(ref-91547-S08887817862001032600000).
3. Switch blower to all speeds. If blower operates in any of the speed positions, go to next step. If blower motor does not operate in all speed positions, see «BLOWER MOTOR MALFUNCTION»(ref-91547-S14359475502001041000000).
4. Place blower motor switch in maximum speed position. Place mode switch in bi-level position. Switch recirculation switch between recirculation and ambient air position. If recirculation door moves between recirculation and ambient air positions, go to next step. If recirculation door does not move between recirculation and ambient air positions, see «AIR RECIRCULATION MALFUNCTION»(ref-91547-S28626607142001041100000).
5. Connect scan tool. Perform RECALIBRATE ALL MOTORS command in INSTRUMENT PANEL SPECIAL FUNCTIONS. Observe current DTC list in INSTRUMENT PANEL MODULE. If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If scan tool does not display any DTCs, go to next step.
6. Place mode switch in each position. If HVAC control head display changes in mode selection, go to next step. If HVAC control module does not respond to changes in mode selection, check for loose wires and/or poor connections at HVAC control head harness connector. If wiring and connections are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.
7. Place mode and defrost switches in each position. If sufficient airflow is coming from correct outlets in each mode, test for intermittent loose wires or bad connections to HVAC control head harness connector. If airflow is not sufficient or air is not coming from correct outlets in each mode, go to next step.
8. Connect scan tool. Observe HTR/DEF/AC DR COMMAND parameter in INSTRUMENT PANEL MODULE data list. Place mode and defrost switches in each mode position. If scan tool indicates HTR/DEF/AC DR COMMAND parameter changes for each change in mode position selected, go to next step. If scan tool indicates HTR/DEF/AC DR COMMAND parameter does not change with each change in mode position selected, check for loose wires and/or poor connections at Instrument Panel Module (IPM) harness connector. If wiring and connections are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION.
9. Turn ignition off. Check continuity in Brown wire between output side of HVAC fuse (10-amp) and terminal No. 5 of mode actuator. Fuse is located in rear fuse box, under rear seat, on driver's side. Check continuity in Gray wire between terminal A1 of IPM harness connector C2 and terminal No. 10 of mode actuator harness connector. (Scheme 10) If continuity exists in both wires, go to next step. If continuity does not exist in either wire, repair open or high resistance in affected wire(s).
10. Inspect air distribution system for a dirty HVAC air filter (if equipped), misaligned air ducts, air leaks or any obstructions to airflow. See «PASSENGER COMPARTMENT AIR FILTER»(ref-91547-S37763215322001042500000) under REMOVAL & INSTALLATION. Repair any problems found. If no problems were found, go to next step.
11. Inspect mode door and mode actuator for a misaligned mode actuator, broken or binding linkages for mode door, an obstruction preventing mode actuator from operating within it's full range of motion, misaligned or missing mode door seals. Find and correct any problems found. If no problems were found, check for loose wires and/or poor connections at mode actuator harness connector. (Scheme 11) If no problems were found, replace mode actuator. See «MODE ACTUATOR»(ref-91547-S08547292932001032600000) under REMOVAL & INSTALLATION.

Scheme 12

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in INSTRUMENT PANEL MODULE SPECIAL FUNCTIONS. Observe current DTC list in Instrument Panel Module (IPM). If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If scan tool did not display any DTCs, go to next step.
3. Turn ignition on. Place blower motor switch in highest speed position. Place mode switch in bi-level position. Move recirculation switch between recirculation and outside air positions. If recirculation door moves from recirculation to outside air positions, test for intermittent loose wires and/or poor connections between recirculation actuator and IPM. (Scheme 11) If recirculation door does not move from recirculation to outside air positions, go to next step.
4. Use scan tool to observe AIR INLET DR COMMAND parameter in IPM data list. Alternatively place recirculation switch in recirculation and outside air positions. If scan tool indicates that AIR INLET DR COMMAND parameter changes for each change in selected position, go to step 6. If scan tool indicates that AIR INLET DR COMMAND parameter does not change for each change in selected position, go to next step.
5. Use scan tool to perform COMMAND RECIRCULATION DOOR from OUTSIDE to RECIRC. Observe AIR OUTLET DOOR COMMANDED parameter. If scan tool indicates that AIR INLET COMMANDED changes, replace recirculation actuator. See «RECIRCULATION ACTUATOR»(ref-91547-S40901149452001042400000) under REMOVAL & INSTALLATION. If scan tool indicates that AIR INLET COMMANDED does not change, check for loose wires and/or poor connections at HVAC control head harness connector. If wiring and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.
6. Check continuity in Brown wire between HVAC fuse (10-amp) and terminal No. 5 of recirculation actuator harness connector. (Scheme 12) If continuity exists, go to next step. If continuity does not exist, repair open in Brown wire.
7. Check continuity in Yellow wire between terminal No. 7 of recirculation actuator harness connector and terminal A7 of Instrument Panel Module (IPM) harness connector. If continuity exists, go to next step. If continuity does not exist, repair open in Yellow wire.
8. Inspect air distribution system for dirty HVAC filter (if applicable), an obstructed air flow, misaligned air ducts and other air leaks. See «PASSENGER COMPARTMENT AIR FILTER»(ref-91547-S37763215322001042500000). Correct any problems found. If no problems were found, go to next step.
9. Inspect recirculation door and actuator for misaligned recirculation actuator, broken recirculation door or binding linkages, an obstruction that prevents recirculation door from moving with in its full range of motion or misaligned or missing recirculation door seals. (Scheme 11) Correct any problems found. If no problems are found, check for loose wires and/or poor connections to recirculation actuator harness connector. If wiring and connectors are okay, inspect IPM harness connectors for loose wires and/or poor connections. If wiring and connectors are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION.

BLOWER MOTOR ALWAYS ON

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Turn ignition on. Turn off all HVAC controls. If blower motor operates, go to next step. If blower motor does not operate, inspect for intermittent loose wires or poor connectors to blower. Repair any damage or loose connections found.
3. Connect scan tool. Observe COMMAND BLOWER parameter in INSTRUMENT PANEL MODULE data list. If scan tool indicates COMMAND BLOWER parameter is near zero percent, go to step 5 . If scan tool indicates COMMAND BLOWER parameter is not near zero percent, go to next step.
4. Use scan tool to perform, COMMAND BLOWER MOTOR OFF. Observe COMMANDED BLOWER parameter. If scan tool indicates COMMAND BLOWER parameter is near zero percent, inspect wires and connectors to blower motor for loose connections or damage. If wires and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION. If scan tool indicates COMMAND BLOWER parameter is not near zero percent, check for loose wires and/or poor connections to Instrument Panel Module (IPM) harness connector. If wiring and connections are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION.
5. Disconnect IPM. If blower motor continues to operate, inspect blower motor control processor harness connectors for loose wires and/or poor connections. If all wiring and connections are okay, replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(ref-91547-S06066472572001042400000) under REMOVAL & INSTALLATION. If blower motor does not continue to operate, check for loose wires and/or poor connections to Instrument Panel Module (IPM) harness connector. If wiring and connections are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION.

Scheme 13

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Turn ignition on. Turn blower knob to each blower position. If blower motor operates in any of the switch positions, check for loose wires and/or connectors to blower switch harness connector. If blower motor does not operate in any of the blower speed switch positions, go to next step.
3. Connect scan tool. Place blower motor in maximum speed position. Observe COMMAND BLOWER parameter in INSTRUMENT PANEL MODULE data list. If scan tool indicates COMMAND BLOWER parameter is near 100 percent, go to next step. If scan tool indicates COMMAND parameter is not near 100 percent, go to step 5.
4. Use scan tool to perform BLOWER MOTOR ON, observe scan tool COMMANDED BLOWER parameter in INSTRUMENT PANEL MODULE data list. If scan tool indicates COMMAND BLOWER parameter is near 100 percent, check for loose wires and connectors at HVAC control head harness connector, if wiring and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION. If wiring and connectors are not okay, repair and retest system. If scan tool indicates COMMAND BLOWER parameter is not near 100 percent, check for loose wires and connectors at Instrument Panel Module (IPM) harness connector. If wiring and connectors are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION. If wiring and connectors are not okay, repair wiring and connectors and retest system.
5. Turn ignition off. Disconnect blower motor harness connector. Turn ignition on. Measure voltage between terminal "B" (Purple wire) and terminal "C" of blower motor harness connector. Switch blower motor to minimum speed position. If battery voltage exists, check for loose wires and connectors at blower motor harness connector. If wiring and connectors are okay, replace blower motor. See «BLOWER MOTOR»(ref-91547-S29390380462001032600000) under REMOVAL & INSTALLATION. If battery voltage does not exist, go to next step.
6. Check continuity between ground and terminal "A" of blower motor harness connector. If continuity exists, repair short to ground in Black wire between blower motor and blower motor command processor harness connector. If continuity does not exist, go to next step.
7. Check continuity in Black wire between terminal "A" of blower motor harness connector and blower motor control harness connector. (Scheme 13) If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Black wire.
8. Check continuity in Brown wire between blower motor control processor harness connector and terminal "C"of blower motor harness connector. If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Brown wire.
9. Connect blower motor control processor and Instrument Panel Module (IPM) harness connectors. Measure voltage between ground and terminal D11 (Gray/Black wire). Connect scan tool. Command blower motor ON and OFF. If voltage is 5 volts with blower motor OFF and 1.5 volts with blower motor ON, go to next step. If voltage is not 5 volts with blower motor OFF and 1.5 volts with blower motor ON, check for loose wires and connectors at blower motor control processor. If wiring and connectors are okay, replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(ref-91547-S06066472572001042400000) under REMOVAL & INSTALLATION. If wiring and connectors are not okay, repair any problems found and retest.
10. Turn ignition off. Disconnect IPM harness connector C1. Turn ignition on. Measure voltage between ground and terminal D11 (Gray/Black wire) of IPM harness connector C1. (Scheme 9) If 5 volts exists, check for loose wires and connectors at IPM. If wiring and connectors are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION. If 5 volts does not exist, go to next step.
11. Check continuity between ground and terminal D11 (Gray/Black wire) of IPM harness connector C1. (Scheme 9) If continuity exists, repair short to ground between IPM and terminal "C" (Gray wire) of blower motor control processor harness connector. (Scheme 13) If continuity does not exist, go to next step.
12. Check continuity between terminal D11 (Gray/Black wire) of IPM harness connector C1 and terminal "C" (Gray wire) of blower motor control processor harness connector. (Scheme 9) If continuity exists, check for loose wires and connectors at blower motor control processor. If wiring and connectors are okay, replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(ref-91547-S06066472572001042400000) under REMOVAL & INSTALLATION. If wiring and connectors are not okay, repair any problems found. If continuity does not exist, repair open in Gray/Black wire.

BLOWER MOTOR MALFUNCTION

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Turn ignition on. Switch blower to all speeds. If blower operates in all speed positions, test for intermittent loose wires and/or poor connections. If blower motor does not operate in all speed positions, go to next step.
3. Connect scan tool. Observe COMMAND BLOWER parameter in the instrument panel module data list. Move blower motor switch from lowest to highest speeds. If scan tool indicates COMMAND BLOWER parameter increases from 10-100 percent, go to next step. If scan tool indicates command blower does not reach 10-199 percent, check for loose wires and/or poor connections at HVAC module harness connector. If wires and connections are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.
4. Turn ignition off. Disconnect blower motor harness connector. Turn ignition on. Connect a DVOM between terminals "A" (Black wire) and "B" (Purple wire) of blower motor harness connector. Adjust blower motor switch from lowest to highest speed positions. If DVOM shows voltage and voltage increases toward highest speed position, check for loose wires and/or poor connections at blower motor harness connector. If wiring and connectors are okay, replace blower motor. See «BLOWER MOTOR»(ref-91547-S29390380462001032600000) under REMOVAL & INSTALLATION. If DVOM does not show voltage and voltage increases toward highest position, go to next step.
5. Check continuity in Orange wire between HVAC BLO fuse (30-amp) and terminal "B" of blower motor control processor harness connector. Fuse is located in rear fuse box, located under rear seat, on driver's side. If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Orange wire.
6. Check continuity between ground and terminal "A" (Black wire) of blower motor control processor harness connector. If continuity exists go to next step. If continuity does not exist, repair open in Black wire between blower motor control processor and ground (located at right side of dashboard).
7. Connect blower motor control processor and Instrument Panel Module (IPM) harness connectors. Measure voltage between ground and terminal D11 (Gray/Black wire) of IPM harness connector C1. (Scheme 9) Move blower motor switch from lowest to highest speed position. If voltage at lowest position is around 4.75 volts and 1.5 volts at highest position, check for loose wires and/or poor connections at blower motor control processor. If wires and connections are okay, replace blower motor control processor. See «BLOWER MOTOR CONTROL PROCESSOR»(ref-91547-S06066472572001042400000) under REMOVAL & INSTALLATION. If voltage is not 4.75 volts at lowest position and 1.5 volts at highest position, check for loose wires and/or poor connections at blower motor harness connector. If wiring and connections are okay, replace blower motor. See «BLOWER MOTOR»(ref-91547-S29390380462001032600000) under REMOVAL & INSTALLATION.

COMPRESSOR CLUTCH DOES NOT DISENGAGE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, command A/C relay ON and OFF. If A/C compressor clutch engages and disengages with each command, go to next step. If A/C compressor clutch does not engage and disengage go to step 7 .
3. Start engine. Depress A/C button to OFF position. Using scan tool, observe COMMANDED A/C parameter in POWERTRAIN CONTROL MODULE (PCM) ENGINE data list. If scan tool displays OFF, inspect PCM for loose wires or connections. If wires and connections are okay, replace PCM. See PCM REMOVAL & REPLACEMENT in ENGINE PERFORMANCE article. If scan tool does not display OFF, go to next step.
4. Use scan tool to observe CONTROL HEAD (DESIRED) parameter in DASH INTEGRATION MODULE (DIM) A/C information list. If scan tool displays A/C OFF, go to next step. If scan tool does not display A/C OFF, go to step 6 .
5. Use scan tool to observe A/C REQUEST parameter in INSTRUMENT PANEL MODULE (IPM) HVAC SYSTEM data list. If scan tool displays NO, check for loose wires and/or poor connections at PCM, If wires and connections are okay, replace PCM. See REMOVAL & INSTALLATION - CARS article in ENGINE PERFORMANCE. If scan tool does not display NO, check for loose wires and/or poor connections at DIM, If wires and connections are okay, replace DIM. See «DASH INTEGRATION MODULE (DIM)»(ref-91547-S16451250002001042600000) under REMOVAL & INSTALLATION.
6. Use scan tool to observe A/C REQUESTED parameter in IPM HVAC SYSTEM data list. If scan tool displays NO, check for loose wires and/or poor connections at DIM harness connector, If wires and connections are okay, replace DIM. If scan tool does not display NO, check for loose wires and/or poor connections at IPM harness connector, If wires and connections are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION.
7. Turn ignition OFF. Disconnect A/C compressor clutch relay. Turn ignition on. If A/C clutch disengages, replace A/C clutch relay. If A/C clutch does not disengage, go to next step.
8. Disconnect A/C compressor. If A/C compressor clutch disengages, repair short to voltage in Dark Green wire between terminal "B" of A/C compressor clutch harness connector and terminal C11 of A/C compressor clutch relay socket. If A/C compressor clutch does not disengage, replace A/C compressor (A/C clutch is not serviceable separately). See «COMPRESSOR»(ref-91547-S27602301482001042500000) under REMOVAL & INSTALLATION.

COMPRESSOR CLUTCH DOES NOT ENGAGE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. With ambient air temperature above 38°F (3°C), start engine. Switch blower motor to high speed position. Place mode switch in defrost position. Place air temperature switch in coldest position. If A/C clutch is engaged, inspect for intermittent loose wires and/or poor connections to A/C compressor. If A/C clutch is engaged, go to next step.
3. Park vehicle in shade or inside. Open windows to ventilate interior of vehicle. Allow A/C system to equalize (about 2 minutes). Turn off ignition. Connect test gauges to high and low pressure PORTS. Record ambient temperature at vehicle. Record readings of low and high side static pressures. Compare both low and high side pressures with allowable limits for the recorded ambient temperature. Perform A/C performance test. See «A/C SYSTEM PERFORMANCE»(ref-91547-S41064610902001032600000) under SYSTEM TESTS. If high and low side pressures are within allowable limits for recorded ambient air temperature and if high and low pressures are within 15 psi (1.0 km/cm 2 ) of each other, go to next step. If high and low side pressures are not within allowable limits for recorded ambient air temperature and/or if high and low pressures are not within 15 psi (1.0 km/cm 2 ) of each other. See LEAK TESTING in GENERAL SERVICING PROCEDURES.
4. Turn ignition on. Using scan tool, observe A/C HIGH SIDE PRESSURE SENSOR parameter in POWERTRAIN data list. Compare A/C high side pressure reading on scan tool to A/C high pressure reading on A/C test gauges. If high side pressure reading on scan tool and test gauges is within 15 psi (1.0 km/cm 2 ) of each other and HVAC control module is not inoperative, go to next step. If high side pressure reading between scan tool and test gauges are not within 15 psi (1.0 km/cm 2 ) of each other, test ground circuit of A/C pressure sensor for an open or high resistance. Repair any damage or loose connectors found. If no problem was found, check for loose wires or connectors at A/C high pressure sensor harness connector. If no problem was found, replace A/C pressure sensor. See «A/C PRESSURE SENSOR»(ref-91547-S27692683052001042500000) under REMOVAL & INSTALLATION.
5. Start engine. Observe COMMANDED A/C parameter in POWERTRAIN data list. Place air temperature switch in coldest position. If scan tool indicates COMMANDED A/C parameter is ON, go to step 12 . If scan tool indicates COMMANDED A/C parameter is not ON, go to next step.
6. Use scan tool to observe A/C CLUTCH (DESIRED) parameter in DASH INTEGRATION MODULE (DIM) A/C INFORMATION LIST. If scan tool indicates that A/C (DESIRED) CLUTCH parameter is ON, go to next step. If scan tool indicates that A/C CLUTCH (DESIRED) parameter is not ON, go to step 8 .
7. Use scan tool to observe A/C CLUTCH (ACTUAL) parameter in DIM A/C INFORMATION LIST. If scan tool indicates A/C CLUTCH (ACTUAL) parameter is ON, go to step 12 . If scan tool indicates A/C CLUTCH (ACTUAL) parameter is not ON, check for loose wires and/or poor connections at Powertrain Control Module (PCM). If wiring and connections are okay, replace PCM. See REMOVAL & INSTALLATION - CARS article in ENGINE PERFORMANCE.
8. Use scan tool to observe CONTROL HEAD (DESIRED) parameter in DIM A/C INFORMATION LIST. If scan tool indicates (DESIRED) parameter is ON, go to next step. If scan tool indicates (DESIRED) parameter is not ON, go to step 11 .
9. Use scan tool to observe PRESSURE STATUS parameter in DIM A/C information list. If scan tool indicates TEMPERATURE STATUS parameter is normal, go to next step. If scan tool indicates, PRESSURE STATUS parameter is not normal, inspect wiring and connectors for intermittent loose wires and/or poor connections.
10. Use scan tool to observe TEMPERATURE STATUS parameter in DASH INTEGRATION MODULE (DIM) A/C information list. If scan tool indicates TEMPERATURE STATUS parameter is okay, check for loose wires and/or poor connections at Dash Integration Module (DIM). If wiring and connectors are okay, replace DIM. See «DASH INTEGRATION MODULE (DIM)»(ref-91547-S16451250002001042600000) under REMOVAL & INSTALLATION. If scan tool indicates temperature status parameter is not okay, check engine for overheating problem and repair as necessary.
11. Use scan tool to observe A/C CONTROL HEAD (DESIRED) parameter IN DIM A/C information list. Place mode switch in defrost position. If scan tool indicates A/C CONTROL HEAD (DESIRED) parameter turns ON and OFF with each command, check for loose wires and/or poor connections at Instrument Panel Module (IPM). If wires and connections are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION. If scan tool indicates A/C CONTROL HEAD (DESIRED) parameter does not turn ON and OFF with each command, check for loose wires and/or poor connections at HVAC control module. If wiring and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.
12. Use scan tool to command A/C compressor clutch relay ON and OFF. If A/C compressor clutch relay turns ON and OFF with each command, go to step 16 . If A/C compressor clutch relay does not turn ON and OFF with each command, go to next step.
13. Turn ignition off. Remove A/C compressor clutch relay. Turn ignition on. Measure voltage between ground and terminal No. 2 (supply side) of A/C compressor clutch relay socket. If battery voltage exists, go to next step. If battery voltage does not exist, replace IGN E fuse (10-amp) in underhood fuse box (located on top of left front fender). If fuse is okay, repair or replace underhood fuse box.
14. Connect positive lead of DVOM to coil input side of compressor clutch relay socket and negative lead to terminal C11 (Dark Green wire) of A/C compressor clutch relay socket. Using scan tool, command A/C clutch relay ON and OFF. If DVOM shows voltage each time scan tool commands A/C clutch relay ON and OFF, check for loose wires or connectors at A/C compressor clutch relay. If wires and connectors are okay, replace A/C compressor clutch relay. If DVOM does not show voltage each time scan tool commands A/C clutch relay ON or scan tool shows voltage when scan tool reads OFF, go to next step.
15. If DVOM shows continuous voltage when scan tool reads ON and OFF, check continuity between ground and terminal "A" of A/C compressor clutch harness connector. If continuity exists, repair short to ground in Dark Green wire between A/C compressor clutch and terminal C11 (Dark Green wire) of A/C clutch relay socket. If DVOM does not show voltage when scan tool reads ON or OFF, check continuity in Dark Green wire between terminal C11 of A/C compressor clutch relay socket and terminal "A" of A/C compressor clutch harness connectors. If continuity does not exist, repair open in Dark Green wire. If continuity exits, check for loose wires and/or poor connections at PCM. If wiring and connectors are okay, replace PCM. See REMOVAL & INSTALLATION - CARS article in ENGINE PERFORMANCE.
16. Turn ignition off. Remove A/C compressor clutch relay from underhood fuse box (located on top of left front fender). Measure voltage between ground and terminal No. 3 of A/C compressor clutch relay. If battery voltage exists, go to next step. If battery voltage does not exist, check A/C fuse (10-amp) in underhood fuse box. If fuse is okay, repair or replace underhood fuse box.
17. Connect a jumper wire between A/C CLU fuse (15-amp) and terminal C11 (Dark Green wire) of A/C compressor clutch relay socket. Turn ignition on. If A/C clutch engages, check for loose wires and/or poor connections at A/C compressor clutch relay socket. If wires and connections are okay, replace A/C compressor clutch relay. If A/C compressor clutch does not engage, go to next step.
18. Check continuity in Dark Green wire between ground and terminal "A" of A/C compressor clutch harness connector. If continuity exists, repair short to ground in Dark Green wire. If continuity does not exist, go to next step.
19. Check continuity in Dark Green wire between terminal "A" of A/C compressor clutch harness connector and terminal C11 of A/C compressor clutch relay socket. If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Dark Green wire.
20. Measure resistance between ground and terminal "B" of A/C compressor clutch. If continuity exists, test for loose connections at A/C compressor clutch. If connectors are okay, replace A/C compressor (A/C clutch is not serviceable separately). See «COMPRESSOR»(ref-91547-S27602301482001042500000) under REMOVAL & INSTALLATION. If continuity does not exist, repair open in black wire between terminal "B" of A/C compressor clutch and ground (located at right rear of cylinder head).

CONTROL HEAD CHANGES SETTINGS BY ITSELF

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Inspect trim fit near A/C and heater control, steering wheel controls and personalization control for interference causing a switch to stick. Correct any problem found. If no problem was found, go to next step.
3. Start engine. Verify all instrument panel outlets are open. Operate all system functions. See «OPERATION»(ref-91547-S08967979982001032600000) . If no problems are found, go to next step. If any problems are found, go to «SELF-DIAGNOSTICS»(ref-91547-S26057743522001032600000) .
4. Verify customer is using correct key to enable personalization process. Verify customer is not accidently activating steering wheel or passenger HVAC controls. If no problem was found, check for loose wires and/or poor connections at HVAC control head. If wire and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.

CONTROL HEAD ILLUMINATION/DISPLAY DOES NOT OPERATE PROPERLY

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step. If DTC B2646 is displayed for Instrument Panel Module (IPM), see appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. The IPM determines exterior light intensity based on voltage input from sun load sensor.
2. Connect scan tool. Turn ignition on. With scan tool, perform DISPLAYS TEST command in INSTRUMENT PANEL SPECIAL FUNCTIONS. If all HVAC control head segments illuminate, go to next step. If all HVAC control module segments do not illuminate, check for loose wires and/or poor connections at HVAC control head. Repair any problems found. If wiring and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.
3. Perform DISPLAYS TEST command in INSTRUMENT PANEL MODULE SPECIAL FUNCTIONS. If all Vacuum Fluorescent (VF) displays illuminate, go to next step. If all VF displays do not illuminate, see appropriate ILLUMINATION/INTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
4. Cover sunload sensor assembly. Turn on headlights. If control head backlighting does not illuminate, see appropriate ILLUMINATION/INTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If backlighting illuminates, adjust dimming control from minimum to maximum intensity. If VF display does not increase in intensity, check for loose wires and/or poor connections at HVAC control head. If wires and connectors are okay, replace HVAC control head. See «HVAC CONTROL HEAD»(ref-91547-S17636773612001032600000) under REMOVAL & INSTALLATION.

DUAL-STAGE ORIFICE MALFUNCTION

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, command A/C orifice relay ON and OFF. If A/C orifice solenoid turns on and off with each command, go to next step. If A/C orifice solenoid does not turn on and off with each command, go to step 5 .
3. Start engine. Select coldest position. Place blower motor switch in maximum speed position. Operate A/C for 5 minutes. Observe EVAPORATOR TEMP STATUS parameter. Command A/C orifice relay ON and OFF. If EVAPORATOR TEMP STATUS parameter changes 2-4°F (1-2°C) with each command, go to next step. If EVAPORATOR TEMP STATUS parameter does not change 2-4°F (1-2°C) with each command, replace orifice solenoid. See «ORIFICE SOLENOID & SCREEN»(ref-91547-S42850355122001042500000) under REMOVAL & INSTALLATION.
4. Use scan tool to observe A/C ORIFICE RELAY parameter. Increase engine RPMs. If scan tool displays that A/C ORIFICE RELAY parameter is inactive above 3500 RPM, inspect for open wires and/or poor connections at DIM harness connector. If scan tool displays that A/C ORIFICE RELAY parameter is active above 3500 RPM, check for loose wires and/or poor connections at Dash Integration Module (DIM). If wires and connections are okay, replace DIM. See «DASH INTEGRATION MODULE (DIM)»(ref-91547-S16451250002001042600000) under REMOVAL & INSTALLATION.
5. Turn ignition off. Remove A/C orifice relay. Turn ignition on. Measure voltage between ground and terminal "A" (Pink/Black wire) of A/C orifice solenoid harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, test switch side of A/C orifice relay socket for open, high resistance or short to ground. Repair any problem found. See «WIRING DIAGRAMS»(ref-91547-S09340817072001032600000) .
6. Measure voltage between switch side supply voltage circuit of A/C orifice relay harness connector and terminal "A" (Pink/Black wire) of A/C orifice solenoid harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, go to step 8 .
7. Measure voltage between ground and coil supply side voltage circuit of A/C orifice relay. If battery voltage exists, go to step 9 . If battery voltage does not exist, test coil side supply voltage circuit of A/C orifice relay for an open, high resistance or short to ground. See «WIRING DIAGRAMS»(ref-91547-S09340817072001032600000) .
8. Turn ignition off. Disconnect A/C orifice solenoid. Reconnect A/C orifice relay. Turn ignition on. Measure voltage between terminal "A" (Pink/Black wire) and "B" (Black wire) of A/C orifice solenoid harness connector. Using scan tool, command A/C orifice relay ON and OFF. If battery voltage exists with each ON command and does not exist with each OFF command, check for loose wires and/or poor connections at A/C orifice solenoid. If wires and connections are okay, replace orifice solenoid. See «ORIFICE SOLENOID & SCREEN»(ref-91547-S42850355122001042500000) under REMOVAL & INSTALLATION. If battery voltage does not exist with each ON command or does not shut off with each OFF command, go to step 11 .
9. Check for voltage between voltage supply circuit terminal and control circuit of A/C orifice solenoid harness connector. Using scan tool, command A/C orifice relay ON and OFF. If voltage exists with each ON command and does not exist with each OFF command, replace A/C orifice solenoid. If voltage does not exist with each ON command or exists with each OFF command, go to next step.
10. Check for voltage between voltage supply terminal and control circuit of A/C orifice solenoid harness connector. Using scan tool, command A/C orifice relay ON and OFF. If voltage exists with each ON command and also exists with each OFF command, test control side of A/C relay for short to ground. If a short to ground does not exist, check for loose wires and connectors at Dash Integration Module (DIM) module. If wires and connectors are okay, replace DIM. See «DASH INTEGRATION MODULE (DIM)»(ref-91547-S16451250002001042600000) under REMOVAL & INSTALLATION. If voltage exists with each ON command and does not exist with each OFF command, test control side of relay for an open or short to voltage. If a short to voltage or an open does not exist, check for loose wires and connectors at DIM module. If wires and connectors are okay, replace DIM.
11. Turn ignition off. Check for voltage between terminals "A" (Pink/Black wire) and "B" (Black wire) of A/C orifice solenoid harness connector. If voltage exists, repair short to voltage in underhood fuse box between CR CONT fuse (10-amp) and supply voltage to HVAC SOL RELAY. If voltage does not exist, check continuity between ground and terminal "B" of A/C orifice solenoid harness connector. If continuity does not exist, repair open in Black wire between terminal "B" of A/C orifice solenoid harness connector and terminal A6 of underhood fuse box.

IMPROPER HVAC CONTROL HEAD RESPONSE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS in INSTRUMENT PANEL MODULE SPECIAL FUNCTION/MISCELLANEOUS tests. Select display DTC function in INSTRUMENT PANEL MODULE. If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If scan tool does not display any DTCs, go to next step.
3. Inspect for a low battery condition or poor battery connections. Recharge or replace battery, or repair connections as necessary. If battery and connections are okay, go to next step.
4. Inspect for stuck or intermittent sticking switch on HVAC control head or steering wheel controls. Repair any problems found, if no problems were found, go to next step.
5. Start engine. Verify all instrument panel outlets are open. Operate all system functions. If no problems are found, system is okay at this time. If any problems are found, perform appropriate symptom test.

OUTSIDE AIR TEMPERATURE DISPLAY INACCURATE

Note. An improperly functioning Engine Coolant Temperature (ECT) sensor and/or Vehicle Speed Sensor (VSS) can affect ambient air temperature reading.

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, inspect ambient air temperature sensor for improper mounting or obstructions.
2. Connect scan tool. Inspect for any current DTCs relating to Engine Coolant Temperature Sensor (ECT) in Powertrain Control Module (PCM). See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no problems were found, go to next step.
3. Connect scan tool. Check for any current DTCs relating to Vehicle Speed Sensor (VSS) in PCM. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If problems were found, check for loose wires and/or poor connections to ambient air temperature sensor. If no problems were found, test ambient air temperature sensor resistance. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table under A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE. If resistance is okay, go to next step. If resistance is not okay, replace ambient air temperature sensor. See «AMBIENT AIR TEMPERATURE SENSOR»(ref-91547-S37932928542001042400000) under REMOVAL & INSTALLATION.

PASSENGER HVAC CONTROL DOES NOT OPERATE PROPERLY

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Turn ignition on. Connect scan tool. Observe AUTO HVAC W/DUAL ZONE OPTION parameter in DASH INTEGRATION MODULE (DIM) SET OPTIONS data list. If scan tool indicates, AUTO HVAC W/DUAL ZONE OPTION is active, go to next step. If scan tool indicates AUTO HVAC W/DUAL ZONE OPTION is not active, using scan tool, enable AUTO HVAC W/DUAL ZONE option in DIM set options data list.
3. Place AUTO control knob in on position. Using scan tool, observe PASS HVAC SWITCH parameter in DRIVER DOOR MODULE data list. Place passenger's air temperature switch in the warmest position. If value of PASS HVAC SWITCH parameter changes, go to next step. If value of PASS HVAC SWITCH parameter does not change, check for loose wires and/or poor connections at passenger's air temperature switch and passenger door module. If wiring and connectors are okay, replace passenger-side temperature control panel. See «PASSENGER-SIDE TEMPERATURE CONTROL PANEL»(ref-91547-S26592961822001042400000) under REMOVAL & INSTALLATION.
4. Connect scan tool. Observe RIGHT PROGRAM NUMBER parameter in INSTRUMENT PANEL MODULE data list. Place passenger's air temperature switch from coldest to warmest position. If RIGHT PROGRAM NUMBER parameter increases, go to next step. If RIGHT PROGRAM NUMBER parameter does not increase, check for loose wires and/or poor connections at Instrument Panel Module (IPM) harness connector. If wiring and connections are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION.
5. Place passenger's air temperature switch in warmest position. Using scan tool, observe RIGHT PROGRAM NUMBER parameter in INSTRUMENT PANEL MODULE data list. Press OFF control knob one time on HVAC control head. If RIGHT PROGRAM NUMBER parameter changes, test for intermittent loose wires and connectors. If RIGHT PROGRAM NUMBER parameter does not change, check for loose wires and/or poor connections at IPM harness connectors. If wiring and connections are okay, replace IPM.

STEERING WHEEL CONTROLS ARE INOPERATIVE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Observe STEERING WHEEL CONTROLS parameter in DASH INTEGRATION MODULE data list. Press each radio and HVAC switch in both directions. If counts change for any switch pressed, go to next step. If counts do not change with any switch pressed, go to step 5 .
3. Use scan tool to observe STEERING WHEEL CONTROLS parameter. Press each radio and HVAC switch in both directions. If counts change for all switches pressed, go to next step. If counts do not change for each switch pressed, test steering wheel controls signal circuits for an open or short to ground between left and right steering wheel controls. See «WIRING DIAGRAMS»(ref-91547-S09340817072001032600000) .
4. Turn on radio, increase and decrease volume with right controls switch on steering wheel. If radio function is controlled with steering wheel switches, see «TEMPERATURE IS TOO COLD IN VEHICLE»(ref-91547-S37259004432001041100000) and «TEMPERATURE IS TOO HOT IN VEHICLE»(ref-91547-S01671318432001041100000) .
5. Deactivate air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. Turn ignition off. Remove and disconnect steering wheel controls. See «STEERING WHEEL CONTROL SWITCHES»(ref-91547-S04468404192001042400000) under REMOVAL & INSTALLATION. Turn ignition on. Connect a jumper wire between terminals No. 1 and No. 5 (Dark Blue wires) of left steering wheel controls harness connector. If counts change, check for loose wires and/or poor connections at left steering wheel control switch. Repair any problems found. If wiring and switches and connections are okay, replace left steering wheel control switch. See «STEERING WHEEL CONTROL SWITCHES»(ref-91547-S04468404192001042400000) under REMOVAL & INSTALLATION.
6. Measure voltage between ground and terminal No. 1 (Purple wire) of right steering wheel control switch harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, go to step 10 .
7. Check continuity of Dark Blue wire between terminal A1 of Dash Integration Module (DIM) and terminal No. 5 of left steering wheel control switch. If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Dark Blue wire.
8. Check for voltage between ground and terminal No. 5 (Dark Blue wire) of left steering wheel control harness connector. If voltage does not exist, go to next step. If voltage exists, repair short to voltage between terminal A1 of DIM and terminal No. 5 of left steering wheel control switch harness connector.
9. Check continuity between ground and terminal No. 5 (Dark Blue wire) of left steering wheel control switch harness connector. If continuity exists, repair short to ground in Dark Blue wire between terminal A1 of DIM and terminal No. 5 of left steering wheel control switch. If continuity does not exist, check for loose wires and/or poor connections at DIM harness connector. If wiring and connectors are okay, replace DIM. See «DASH INTEGRATION MODULE (DIM)»(ref-91547-S16451250002001042600000) under REMOVAL & INSTALLATION.
10. Check continuity of Dark Blue wire between terminal No. 6 of right steering wheel control switch and terminal A1 of Dash Integration Module (DIM). If continuity exists, go to next step. If continuity does not exist, repair open or high resistance in Dark blue wire.
11. Check continuity between ground and terminal No. 6 (Dark Blue wire) of right steering wheel control switch harness connector. If continuity exists, repair short to ground in Dark Blue wire. If continuity does not exist, enable air bag system and operate steering wheel controls system to verify repair.

TEMPERATURE IS TOO COLD IN VEHICLE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in IPM. Observe all current DTCs in Instrument Panel Module (IPM). If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If DTCs are not displayed, go to next step.
3. Place blower motor switch in each speed position. If blower motor operates in any position, go to next step. If blower motor does not operate in any position, see «BLOWER MOTOR DOES NOT OPERATE IN ANY MODE»(ref-91547-S24653280212001032600000) .
4. Place blower motor in each speed position. If blower motor operates in all speed positions but problem only exists when defrost is on, go to next step. If problem does not only exist when defrost is on, go to step 8 . If blower motor does not operate in all speed positions, see «BLOWER MOTOR MALFUNCTION»(ref-91547-S14359475502001041000000) .
5. Start engine. Turn HVAC controls off. If A/C compressor clutch engages, see «COMPRESSOR CLUTCH DOES NOT DISENGAGE»(ref-91547-S34933947512001041000000) . If compressor clutch does not engage, go to next step.
6. Inspect cooling system for low coolant level, leaking or kinked heater or radiator hoses, loose or worn drive belts or leaking radiator cap or missing cap seal. Correct any problems found and go to step 15 . If no problems were found, go to next step.
7. Check heating system performance. See «HEATING SYSTEM PERFORMANCE»(ref-91547-S05460661522001042300000) under SYSTEM TESTS. Correct any problems found and go to step 15 . If no problems were found, go to next step.
8. Inspect upper and lower, right and left, air temperature sensors for proper installation. Correct any problems found and go to step 15 . If no problems are found, go to next step.
9. Start engine. Fully open all HVAC panel outlets. Place temperature switch at 75°F (24°C). Place mode switch in panel (upper) position. Set blower speed to illuminate 2 bars on fan speed indicator. Place passenger's temperature switch in neutral position. Test airflow through inside air temperature sensor by placing a 2" (5 cm) square piece of paper over sensor air inlet. If suction holds paper in place, go to next step. If suction does not hold paper in place, inspect for blocked or disconnected aspiration hose and repair as necessary and go to step 15 .
10. Turn ignition on. Connect scan tool. Cover sunload sensor. Start engine. Place temperature switch at 75°F (24°C). Place passenger's air temperature switch in neutral position. Using scan tool, observe both RIGHT and LEFT SOLAR SENSOR DATA parameters on INSTRUMENT PANEL MODULE (IPM) OPEN/SHORT data list. If scan tool indicates RIGHT and LEFT SUNLOAD SENSOR DATA parameters are more than 224 counts, go to next step. If scan tool indicates RIGHT and LEFT SUNLOAD SENSOR parameters are 224 counts or more, inspect sunload sensor for loose wires and connector. Repair as necessary and go to step 15 . If wiring and connectors are okay, replace sunload sensor, see «SUN LOAD SENSOR»(ref-91547-S18469500342001042400000) under REMOVAL & INSTALLATION and go to step 15 .
11. Uncover sunload sensor. Shine a light at right and then left side of sunload sensor assembly. If counts change in relation to amount of light and which side of sunload sensor assembly is being illuminated, go to next step. If counts do not change in relation to amount of light and which side of the sunload sensor assembly is being illuminated, inspect sunload sensor for loose wires and connector. Repair as necessary and go to step 15 . If wiring and connectors are okay, replace sunload sensor, see «SUN LOAD SENSOR»(ref-91547-S18469500342001042400000) under REMOVAL & INSTALLATION and go to step 15 .
12. Place thermometer near inside air temperature sensor and upper and lower right and left air temperature sensors. Using scan tool, observe DATA parameters in INSTRUMENT PANEL MODULE HVAC SENSOR data list for INSIDE AIR TEMP, RIGHT A/C DUCT TEMP, LEFT A/C DUCT TEMP, LEFT A/C DUCT TEMP, RIGHT HTR DUCT TEMP and LEFT HTR. DUCT TEMP. If scan tool readings are within 5°F to - 5°F (3°C to -3°C) of thermometer readings, go to next step. If scan tool readings are not within 5°C to - 5°F (3°C to -3°C) of thermometer readings, check for loose wires and/or poor connections at harness connector for suspected sensor. Repair as necessary and go to step 15 . If wires and connections are okay, test suspect sensor. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table under A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE. If sensor tests okay, check for loose wires and/or poor connections at IPM. Repair as necessary and go to step 15 . If wires and connectors are okay, replace IPM, see «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION and go to step 15 . If sensor does not test as specified, replace suspect sensor, see «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION and go to step 15 .
13. If customer needs to frequently change the set temperature to maintain comfort, see «A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE»(ref-91547-S26811899752001041200000) . If customer does not need to frequently change the set temperature to maintain comfort, go to next step.
14. Inspect for a blocked or disconnected aspiration hose. Repair as necessary and go to next step.
15. Connect scan tool. Turn ignition on. Using scan tool, perform ADJUST TEMPERATURE OFFSET in INSTRUMENT PANEL MODULE SPECIAL FUNCTION/SET options as needed.

TEMPERATURE IS TOO HOT IN VEHICLE

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Perform RECALIBRATE ALL MOTORS command in INSTRUMENT PANEL MODULE SPECIAL FUNCTIONS menu. Observe current DTC list in instrument panel module. If scan tool displays any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If no DTCs are found, go to next step.
3. Connect scan tool. Turn ignition on. Command A/C orifice relay, in dash integration module, ON and OFF. If A/C orifice solenoid turns ON and OFF with each command, go to next step. If A/C orifice solenoid does not turn ON and OFF with each command, see «DUAL-STAGE ORIFICE MALFUNCTION»(ref-91547-S42053501612001041200000) .
4. Place blower motor switch in each position. If blower motor operates in any position, go to next step. If blower motor does not operate in any position, see «BLOWER MOTOR MALFUNCTION»(ref-91547-S14359475502001041000000) .
5. Verify blower motor operates in each position. If blower motor operates in each position, go to next step. If blower motor does not operate in each position, see «BLOWER MOTOR MALFUNCTION»(ref-91547-S14359475502001041000000) .
6. With ambient air temperature above 38°F (3°C), cover sunload sensor, start engine and fully open all panel outlets. Select fully cold position. Place blower motor switch in maximum speed position. Place mode switch in panel (upper) position. Verify vent (ambient air) indicator is not illuminated. If A/C clutch engages, go to next step. If A/C clutch does not engage, see «COMPRESSOR CLUTCH DOES NOT ENGAGE»(ref-91547-S23970048512001041000000) .
7. Check A/C system performance. See «A/C SYSTEM PERFORMANCE»(ref-91547-S41064610902001032600000) under SYSTEM TESTS. Correct any condition found. If condition was not found and corrected, go to next step.
8. Inspect upper and lower right and left air temperature sensors for proper installation. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION. Correct or repair any problem found. If no problems were found, go to next step.
9. Start engine. Fully open all panel outlets. Adjust temperature setting to 75°F (24°C) position. Place mode switch in panel (upper) position. Set blower speed so 2 bars illuminate on fan speed indicator. Place air temperature switch in neutral position. Inspect airflow through inside air temperature sensor by placing a 2" (5 cm) square piece of paper over sensor air inlet. If paper stays in place, go to next step. If suction does not hold paper in place, inspect for blocked or disconnected aspiration hose and repair.
10. Turn engine off. Connect scan tool. Cover sunload sensor. Start engine. Select temperature 75°F (24°C). Place air temperature switch in neutral position. Using scan tool, observe RIGHT and LEFT SUNLOAD SENSOR DATA parameters in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates that RIGHT and LEFT SUNLOAD SENSOR DATA parameters are 224 counts or more, go to next step. If scan tool indicates that RIGHT and LEFT SUNLOAD SENSOR parameters are less than 224 counts, check for loose wires and/or poor connections at sunload harness connector. If wires and connectors are okay, replace sunload sensor. See «SUN LOAD SENSOR»(ref-91547-S18469500342001042400000) under REMOVAL & INSTALLATION.
11. Uncover sunload sensor. Direct a light source at right and left side of sensor assembly. If count changes are similar from one side to the other of sunload sensor, go to next step. If count changes are not similar from one side to the other of sunload sensor, check for loose wires and poor connectors at sunload sensor. If wires and connections are okay, replace sunload sensor.
12. Place thermometer near inside air temperature sensor and upper and lower right and left air temperature sensors. Using scan tool, observe DATA parameters in INSTRUMENT PANEL MODULE HVAC SENSOR data list for INSIDE AIR TEMP, RIGHT A/C DUCT TEMP, LEFT A/C DUCT TEMP, LEFT A/C DUCT TEMP, RIGHT HTR DUCT TEMP and LEFT HTR. DUCT TEMP. If scan tool readings are within 5°F to - 5°F (3° to -3°C) of thermometer readings, go to next step. If scan tool readings are not within 5°F to - 5°F (3°C to -3°C) of thermometer readings, check for loose wires and/or poor connections at harness connector for suspected sensor. If wires and connections are okay, test suspect sensor. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table under A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE. If sensor tests okay, check for loose wires and/or poor connections at IPM. If wires and connectors are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION. If sensor does not test as specified, replace suspect sensor. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION.
13. If customer needs to adjust temperature frequently to maintain comfort, see «A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE»(ref-91547-S26811899752001041200000) . If customer does not need to change set temperature frequently to maintain comfort, go to next step.
14. Inspect for a blocked or disconnected aspirator hose. Correct any damage found.

TEMPERATURE VARIATION BETWEEN DRIVER AND PASSENGER OUTLETS

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(ref-91547-S34777884642001040900000) under TROUBLE SHOOTING. After performing system check, go to next step.
2. Connect scan tool. Turn ignition on. Using scan tool, perform RECALIBRATE ALL MOTORS command in INSTRUMENT PANEL MODULE SPECIAL FUNCTIONS. Observe current DTC list in instrument panel module. If scan tool displays DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITION»(ref-91547-S41538562112001032600000) table under SELF-DIAGNOSTICS. If no DTCs exist, go to next step.
3. If problem occurs when A/C is on, go to next step. If problem occurs when A/C is not on, go to step 9 .
4. With ambient air temperature above 38°F (3°C), cover sunload sensor assembly. Start engine. Fully open all panel outlets. Select coldest position. Place mode switch in panel (upper) position and blower motor switch at maximum speed. Place passenger air temperature switch in neutral position. Verify that vent (ambient air) indicator is not illuminated. If difference between right and left center panel outlet temperatures are greater than specified value, check A/C system performance. See «A/C SYSTEM PERFORMANCE»(ref-91547-S41064610902001032600000) under SYSTEM TESTS. If test does not reveal problem, go to next test.
5. Inspect upper and lower right and left air temperature sensors for proper installation. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION. Repair any problems found. If no problems are found, go to next step.
6. Connect scan tool. Cover sunload sensor assembly. Start engine. Select temperature 75°F (24°C). Place air temperature switch in neutral position. Using scan tool, observe RIGHT and LEFT SOLAR DATA parameters in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates RIGHT and LEFT SUNLOAD SENSOR DATA parameters are more than 224 counts, go to next step. If scan tool indicates RIGHT and LEFT SENSOR DATA parameter is 224 counts or less, check for loose wires and/or poor connections at sunload sensor assembly. If wires and connectors are okay, replace sunload sensor assembly. See «SUN LOAD SENSOR»(ref-91547-S18469500342001042400000) under REMOVAL & INSTALLATION.
7. Uncover sunload sensor. Direct a light source at right and then left side of sunload sensor assembly. If sunload sensor counts correspond to proper side of sunload sensor, go to next step. If sunload sensor counts do not correspond to proper side of sunload sensor, check for loose wires and/or poor connections at sunload sensor assembly. If wires and connectors are okay, replace sunload sensor assembly.
8. Place thermometer near inside air temperature sensor and upper and lower right and left air temperature sensors. Using scan tool, observe DATA parameter in INSTRUMENT PANEL MODULE HVAC SENSOR data list for INSIDE AIR TEMP, RIGHT A/C DUCT TEMP, LEFT A/C DUCT TEMP, LEFT A/C DUCT TEMP, RIGHT HTR DUCT TEMP and LEFT HTR. DUCT TEMP. If scan tool readings are within 5°F to - 5°F (3°C to -3°C) of thermometer readings, go to next step. If scan tool readings are not within 5°F to - 5°F (3°C to -3°C) of thermometer readings, check for loose wires and/or poor connections at harness connector for suspected sensor. If wires and connections are okay, test suspect sensor. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table under A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE. If sensor tests okay, check for loose wires and/or poor connections at IPM. If wires and connectors are okay, replace IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION. If sensor does not test as specified, replace suspect sensor. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION.
9. Cover sunload sensor assembly. Start engine. Fully open all panel outlets. Select warmest temperature position. Place mode switch in floor (lower) position. Place blower motor switch in maximum speed position. Place passenger-side temperature control switch in neutral position. If difference between right and left outlet temperatures is greater than 10°F (6°C), go to next step. If difference between right and left outlet temperatures is not greater than 10°F (6°C), system is okay at this time.
10. Inspect cooling system for low coolant level, leaking or kinked heater or radiator hoses, loose or warn drive belts or leaking radiator cap or missing cap seal. Correct any problems found. If no problems were found, go to next step.
11. Check heating system performance. See «HEATING SYSTEM PERFORMANCE»(ref-91547-S05460661522001042300000) under SYSTEM TESTS. Correct any problems found. If no problems were found, go to next step.
12. Inspect upper and lower right and left air temperature sensors for proper installation. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION. Correct or repair any problems found. If no problems were found, go to next step.
13. Turn engine off. Connect scan tool. Cover sunload sensor. Start engine. Select temperature 75°F (24°C). Place air temperature switch in neutral position. Using scan tool, observe RIGHT AND LEFT SUNLOAD SENSOR DATA parameters in INSTRUMENT PANEL MODULE OPEN/SHORT data list. If scan tool indicates that RIGHT and LEFT SUNLOAD SENSOR DATA parameters are 224 counts or more, go to next step. If scan tool indicates that RIGHT and LEFT SUNLOAD SENSOR DATA parameters are less than 224 counts, check for loose wires and/or poor connections at sunload harness connector. If wires and connectors are okay, replace sunload sensor. See «SUN LOAD SENSOR»(ref-91547-S18469500342001042400000) under REMOVAL & INSTALLATION.
14. Uncover sunload sensor. Direct a light source at right and left side of sensor assembly. If count changes are similar from one sunload sensor to the other, go to next step. If count changes are not similar from one sunload sensor to the other, check for loose wires and poor connectors at sunload sensor. If wires and connections are okay, replace sunload sensor.
15. Place thermometer near inside air temperature sensor and upper and lower right and left air temperature sensors. Using scan tool, observe DATA parameters in INSTRUMENT PANEL MODULE HVAC SENSOR data list for INSIDE AIR TEMP, RIGHT A/C DUCT TEMP, LEFT A/C DUCT TEMP, LEFT A/C DUCT TEMP, RIGHT HTR DUCT TEMP and LEFT HTR. DUCT TEMP. If scan tool readings are within 5°F to - 5°F (3°C to -3°C) of thermometer readings, system is okay at this time. If scan tool readings are not within 5°F to - 5°F (3°C to -3°C) of thermometer readings, go to next step.
16. Check for loose wires and/or poor connections at harness connector of suspected sensor. If wires and connections are okay, test suspect air temperature sensor resistance. See «SENSOR RESISTANCE»(ref-91547-S09641971632001042000000) table under A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE. If resistance measurement is near sensor resistance value, check for loose wires and/or poor connections at IPM. See «INSTRUMENT PANEL MODULE (IPM)»(ref-91547-S37515822782001042500000) under REMOVAL & INSTALLATION. If wires and connectors are okay, replace IPM. If sensor does not test as specified, replace suspect sensor. See «AIR TEMPERATURE SENSORS»(ref-91547-S37006549882001042400000) under REMOVAL & INSTALLATION.

SYSTEM TESTS

A/C SYSTEM PERFORMANCE

Note. Perform test with ambient air temperature 60°F (16°C) or more. Do not provide additional airflow to front of vehicle during test. If you were sent here from a DTC test, clear DTC upon completion of test.

1. Park vehicle in shaded area. Open windows to ventilate interior. Vent exhaust. Install gauge set. Measure and record ambient temperature and relative humidity. Close doors and windows. Open driver's window 5-6" (127-152 mm). Set controls to AUTO, select maximum blower speed, and set temperature control to coldest value. Insert thermometer into center outlet.
2. Set transmission in Park or Neutral. Start and idle engine for 5 minutes. Record outlet temperature, and high and low side pressures. Turn engine off. Compare readings with specifications. See «A/C PERFORMANCE SPECIFICATIONS (3.5L ENGINE)»(ref-91547-S14693890672001032600000) or «A/C PERFORMANCE SPECIFICATIONS (4.0L ENGINE)»(ref-91547-S21553216832001032600000) table. If both high and low side pressures are not within specified values, check refrigerant system for proper operation.

A/C PERFORMANCE SPECIFICATIONS (3.5L ENGINE)

A/C PERFORMANCE SPECIFICATIONS (4.0L ENGINE)

HEATING SYSTEM PERFORMANCE

1. Inspect cooling system for low coolant level, loose or worn drive belt, leaking, kinked or damaged heater or radiator hoses or damaged radiator cap. Repair any problems found. If no problems were found, start engine and allow engine to idle in park. If engine reaches normal operating temperature, go to next step. If engine does not reach normal operating temperature, see appropriate article in ENGINES.
2. Move vehicle outdoors. Close all doors, windows and hood. Run engine until it reaches normal operating temperature. Place thermometer into center instrument panel outlet. Select vent position of mode control button. Select maximum blower speed. Place temperature control knob to maximum hot position. Measure and record temperature of air delivered. If air temperature is near 120°F (49°C) at 0°F (18°C), 135°F (57°C) at 32°F (0°C) or 140°F (60°C) at 50°F (10°C), inspect cowl, air inlet valve and HVAC module case for cold air leaks. If air temperature is not near specified values, go to next step.
3. Start engine and allow to idle. Depress mode control button until lower position is displayed. Select lowest blower speed position. Turn temperature control knob to maximum hot position. Feel for a minimum temperature of 85°F (24°C) at heater inlet and outlet hoses. If heater inlet hose is warm and outlet hose is cold, check thermostat for proper condition and installation. Correct any problems found. If thermostat was okay, go to next step.
4. Remove heater hoses and back flush heater core. Reconnect heater hoses. Drain and refill engine coolant. Start engine and allow to idle. Depress mode control button until lower position is displayed. Select lowest blower speed position. Turn temperature control knob to maximum hot position. Feel for a minimum temperature of 85°F (24°C) at heater inlet and outlet hoses. If both heater inlet and outlet hoses feel warm, operate system to very repair. If both heater core inlet and outlet hoses do not feel warm, replace heater core. See «HEATER CORE»(ref-91547-S16559946032001042500000) under REMOVAL & INSTALLATION.