Chevrolet Trax: Air conditioning compressor malfunction (C60)

Diagnostic Instructions

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

Diagnostic Fault Information

Circuit/System Description

The A/C compressor uses a conventional belt driven magnetic clutch to engage and mechanically turn the compressor. When the A/C switch is pressed, the HVAC control module sends an A/C request message to the ECM via serial data. If specific criteria are met, the ECM then grounds the A/C compressor clutch relay control circuit, which will switch the A/C compressor clutch relay. With the relay contacts closed, battery voltage is supplied to the permanently grounded A/C compressor clutch. The A/C compressor clutch will then be activated.

Diagnostic Aids

The following conditions must be met in order to turn on the A/C compressor:

• Battery voltage is between 9-18 V.
• Engine coolant temperature is less than 124ºC (255ºF).
• 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 3ºC (38ºF).
• ECM does not detect excessive torque load.
• ECM does not detect insufficient idle quality.
• The ambient temperature is above 1ºC (34ºF).
• Blower motor must be in any other position than off.
• A/C switch is depressed.

Reference Information

Schematic Reference

HVAC Schematics (Encore), HVAC Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Manual HVAC Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Refer to HVAC System Malfunction (C60) before performing this procedure

1. Ignition ON, press and release the A/C switch several times.
2. Verify the HVAC control module scan tool A/C Switch parameter changes between Active and Inactive

If the parameter does not change

Replace the K33 HVAC Control Module.

If the parameter changes

3. Set A/C system to coolest setting with blower ON.
4. Press and release the A/C switch several times.
5. Verify the ECM scan tool A/C Request Signal parameter changes between YES and NO.

If the parameter does not change

Refer Circuit/System Testing

If the parameter changes

6. Verify the A/C compressor clutch engages when commanding the ECM A/C Relay output function On and Off with a scan tool.

If the A/C compressor clutch does not engage

Refer to DTC P0645, P0646, or P0647

If the A/C compressor clutch engages

7. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
2. Install a 3 A jumper wire between the signal circuit terminal 5 and ground, A/C switch depressed.
3. Verify the scan tool ECM A/C Request Signal parameter changes between YES and NO.

If the parameter does not change

1. Ignition OFF, remove the jumper wire and disconnect the X2 harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC Control Module.

If the parameter changes

4. Replace the K33 HVAC Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• HVAC Component Replacement Reference (C60)
• Control Module References for HVAC control module replacement, programming and setup

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