• 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.

For symptom byte information, refer to Symptom Byte List.

This A/C system uses a conventional clutch to engage and mechanically turn the compressor and a variable displacement solenoid valve to alter the amount of displacement created by the turning of the compressor. The HVAC control module provides both switched battery voltage and a pulse width modulated ground to the variable displacement solenoid valve. When the A/C switch is pressed, the HVAC control module grounds the variable displacement solenoid using a (PWM) signal in order to determine the amount of compressor displacement. The performance of the A/C compressor is based on adjusted interior temperature and engine load.

• Ignition ON.
• The HVAC control module is ON.

A PWM greater than 10% is sent but no current is read back.

Measured current is above threshold of 815 mA.

The A/C compressor is disabled.

• The A/C compressor is disabled.
• Output will be switched off for hardware protection.

The condition for setting the DTC is no longer present.

HVAC Schematics

Master Electrical Component List

Automatic HVAC Description and Operation

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

Control Module References for scan tool information

1. Ignition OFF, disconnect the harness connector at the Q46 A/C Compressor Solenoid Valve. Connect a test light between terminals 1 and 2 of the harness connector. Ignition ON.
2. Verify the test light turns on and off when commanding the Q46 A/C Compressor Solenoid Valve ON and OFF with the scan tool.
• If the test light does not turn ON and OFF
1. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
2. Test for less than 1 V between ground and each control circuit terminal listed below:
• terminal 10
• terminal 11
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF.
4. Test for infinite resistance between ground and each control circuit terminal listed below:
• terminal 10
• terminal 11
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
5. Test for less than 2 Ω in each of the control circuits end to end listed below:
• Q46 A/C Compressor Solenoid Valve terminal 1 and K33 HVAC Control Module terminal 10
• Q46 A/C Compressor Solenoid Valve terminal 2 and K33 HVAC Control Module terminal 11
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K33 HVAC Control Module.
• If the test light turns ON and OFF
3. Test the Q46 A/C Compressor Solenoid Valve or replace the G1 A/C Compressor.

1. Ignition OFF, disconnect the harness connector at the Q46 A/C Compressor Solenoid Valve.
2. Test for 7–15 Ω between B+ terminal 2 and control terminal 1.
• If less than 7 Ω or greater than 15 Ω

  Replace the G1 A/C Compressor.

• If between 7–15 Ω
3. Test for infinite resistance between each terminal and the Q46 A/C Compressor Solenoid Valve housing/case.
• If less than infinite resistance

  Replace the G1 A/C Compressor.

• If infinite resistance
4. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

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