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Air Temperature Malfunction




Air Temperature Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

Only C68

With the temperature switch at the Radio/HVAC control, the desired air temperature flap position can be put in. The selected value is sent to the HVAC control module via the LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motor and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motor puts the mixed air flap into the calculated position, in order to reach the selected temperature.

Only CJ2

With the temperature switches at the Radio/HVAC control, the wished air temperature flap position can be put in. The selected values are sent to the HVAC control module via LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors put the mixed air flaps into the calculated position, in order to reach the put in temperature.

Diagnostic Aids

Check the following mechanical fault sources:

* Air distribution box
* Air distribution hoses/air distribution ducts

Reference Information
Schematic Reference

HVAC Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Automatic HVAC Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Ignition ON, press and release the POWER switch. Verify the scan tool Front HVAC System Status parameter changes between Off and On.

• If not the specified value, replace the A20 Radio/HVAC Controls.

2. Ignition ON, measure actual inside air temperature using a thermometer. Compare this value to the scan tool Passenger Compartment Air Temperature parameter. The measured temperature should be within 5°C (9°F) difference of parameter value.

• If not within the specified range, refer to DTC B0163, B0183, or B1405 (CJ2) (B0163)DTC B0163, B0183, or B1405 (C68) (B0163).

3. Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct Actual parameter. The measured temperature should be within 5°C (9°F) difference of appropriate Duct Actual parameter value.

• If not within the specified range, refer to DTC B0173, B0178, B0509, B0514 or B3933 (B0173).

4. Measure actual evaporator temperature using a thermometer. Compare this value to the scan tool A/C Evaporator Temperature Sensor parameter. The measured temperature should be within 5°C (9°F) difference of parameter value.

• If not within the specified range, refer to DTC B0173, B0178, B0509, B0514 or B3933 (B0173).

5. Observe the scan tool Sunload parameter. The reading should be between 50-1 150 W/m(2) and change with sunlight intensity.

• If not within the specified range or not change, refer to DTC B0163, B0183, or B1405 (CJ2) (B0163)DTC B0163, B0183, or B1405 (C68) (B0163).

6. Engine is running, activate and deactivate the A/C switch. Verify the A/C compressor can be activated and deactivated.

• If the A/C compressor cannot be activated or deactivated, refer to Air Conditioning Compressor Malfunction (Air Conditioning Compressor Malfunction).

7. Verify the engine reaches its operating temperature.

Circuit/System Testing

Only C68
1. Ignition ON, press and release the temperature increase switch. Verify the scan tool Left Temperature Switch parameter changes between Up and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

2. Press and release the temperature decrease switch. Verify the scan tool Left Temperature Switch parameter changes between Down and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

3. Press and release the AUTO Switch. Verify the scan tool Auto HVAC Button parameter changes between Active and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

4. If all circuits test normal, replace the M6L Air Temperature Door Actuator - Left and verify the M6L Air Temperature Door Actuator - Left can be put into all positions.

Only CJ2
1. Ignition ON, press and release the driver side temperature increase switch. Verify the scan tool Left Temperature Switch parameter changes between Up and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

2. Press and release the driver side temperature decrease switch. Verify the scan tool Left Temperature Switch parameter changes between Down and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

3. Press and release the passenger side temperature increase switch. Verify the scan tool Right Temperature Switch parameter changes between Up and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

4. Press and release the passenger side temperature decrease switch. Verify the scan tool Right Temperature Switch parameter changes between Down and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

5. Press and release the AUTO Switch. Verify the scan tool Auto HVAC Button parameter changes between Active and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

6. Press and release the ZONE Switch. Verify the scan tool MULTI-ZONE Switch parameter changes between Active and Inactive.

• If not the specified value, replace the A20 Radio/HVAC Controls.

7. Verify the M6L Air Temperature Door Actuator - Left can be put into all positions.

• If the M6L Air Temperature Door Actuator - Left cannot be put into all positions, replace the M6L Air Temperature Door Actuator - Left and verify the M6L Air Temperature Door Actuator - Left can be put into all positions.

8. If all circuits test normal, replace the M6R Air Temperature Door Actuator - Right and verify the M6R Air Temperature Door Actuator - Right can be put into all positions..

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Temperature Valve Actuator Replacement - Left Side (Left Hand Drive) (Temperature Valve Actuator Replacement - Left Side (Left Hand Drive))
* Temperature Valve Actuator Replacement - Right Side (Temperature Valve Actuator Replacement - Right Side)
* Control Module References (Programming and Relearning) for HVAC control module replacement, setup, and programming

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