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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 238 (HVAC System - Automatic) >> Diagnostic Information and Procedures >> Air Conditioning Compressor Malfunction >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2017 Cadillac ATS. 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.

  1. Ignition ON, press and release the A/C Switch.
  2. Verify the HVAC control module scan tool A/C Request Signal parameter changes between Active and Inactive.
    • If the parameter does not change 

      Replace the A20 Radio/HVAC Controls.

    • 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 Active and Inactive.
    • If the parameter does not change 

      Replace the K33 HVAC Control Module.

    • 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 engages 
  7. Engine ON.
  8. Verify the HVAC 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 B393B 

    • If the parameter does change 
  9. All OK.
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