Heating and Air Conditioning: Testing and Inspection

Inspection and Verification

CAUTION: Diagnosis by substitution from a donor vehicle is NOT acceptable. Substitution of control modules does not guarantee confirmation of a fault, and may also cause additional faults in the vehicle being tested and/or the donor vehicle.

1. Verify the customer concern.
2. Visually inspect for obvious signs of damage and system integrity.





3. Listen for any unusual noises during climate control system operation.
4. Inspect the refrigerant system with an ultraviolet (UV) lamp for traces of UV sensitive leak trace dye.
5. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step
6. If the cause is not visually evident, check Climate Control Module, Engine Control Module (ECM), Fuel Fired Booster Heater and Central Junction Box (CJB) for Diagnostic Trouble Codes (DTCs) and refer to the DTC Index.