Air Conditioning Compressor Malfunction
Air Conditioning Compressor 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
The HVAC control module supplies battery voltage to the A/C compressor. When the A/C switch is pressed, the HVAC control module provides a pulse width modulation (PWM) signal to the A/C compressor in order to command the performance of the A/C compressor. The performance of the A/C compressor is regulated according to adjusted interior temperature on the basis of characteristic lines. Therefore the HVAC control module grounds the A/C compressor with the PWM signal.
Diagnostic Aids
The following conditions must be met in order for the HVAC control module to turn on the A/C compressor:
* Battery voltage is between 9-18 V
* Engine coolant temperature is less than 124°C (255°F)
* Engine speed is greater than 600 RPM
* Engine speed is less than 5 500 RPM
* A/C high side pressure is between 269-2 929 kPa (39-425 PSI)
* Throttle position is less than 100%
* Evaporator temperature is greater than 3°C (38°F)
* ECM does not detect immoderate torque load
* ECM does not detect insufficient idle quality
* The ambient temperature is above 1°C (34°F)
Reference Information
Schematic Reference
HVAC Schematics (C68) (HVAC Schematics (C68))HVAC Schematics (CJ2) (HVAC Schematics (CJ2))
Connector End View Reference
Component Connector End Views (Connector Views)
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 Testing
Note: Before executing Circuit/System Testing, all conditions shown in Diagnostic Aids must be met.
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 Control.
2. Ignition ON, press and release the A/C Switch. Verify the scan tool A/C Switch parameter changes between Active and Inactive.
• If not the specified value, replace the A20 Radio/HVAC Control.
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 Control.
4. If all circuits test normal, replace the K33 HVAC Control Module and verify the Q46 Air Conditioning Compressor Valve can be activated and deactivated. If the Q46 Air Conditioning Compressor Valve cannot be activated or deactivated, replace the Q46 Air Conditioning Compressor Valve.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Air Conditioning Compressor Replacement (V6) (Removal and Replacement)Air Conditioning Compressor Replacement (LAF) (Removal and Replacement)
* Radio Control Assembly Replacement (Radio Control Assembly Replacement)
* Control Module References (Programming and Relearning)for HVAC Control Module replacement, setup, and programming