Circuit/System Verification

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

Refer to HVAC System Malfunction before performing this procedure.

Ignition ON, press and release the A/C Switch.
Verify the body control module scan tool A/C Switch parameter changes between Active and Inactive.
- If the parameter does not change
  Replace the A26 Heater and Air Conditioning User Interface Control - Front.
- Go to next step: If the parameter changes
Set A/C system to coolest setting with blower ON.
Press and release the A/C switch several times.
Verify the ECM scan tool A/C Request Signal parameter changes between Active and Inactive.
- If the parameter does not change
  Replace the K9 Body Control Module.
- Go to next step: If the parameter changes
Verify the A/C compressor clutch engages and disengages when commanding the ECM A/C Compressor Clutch Relay output function On and Off with a scan tool.
- If the A/C compressor clutch does not engage or disengage as commanded
  Refer to DTC P0645, P0646, or P0647
- Go to next step: If the A/C compressor clutch engages and disengages as commanded
Engine ON, A/C system ON.
Verify the body control module scan tool A/C Compressor Refrigerant Solenoid Valve Command parameter changes with varying cooling loads.
- If the parameter does not change
  Refer to DTC B2AEF or B2AF0-B2AF4
- Go to next step: If the parameter changes
Refer to Air Conditioning (A/C) System Performance Test