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.

Climate Control System

NOTE:
If a control module or component is suspect and the vehicle remains under manufacturer warranty, refer to the Warranty Policy and Procedures manual (section B1.2), or determine if any prior approval program is in operation, before the replacement of a component.

NOTE:
Generic scan tools may not read the codes listed, or may read only 5-digit codes. Match the 5 digits from the scan tool to the first 5 digits of the 7-digit code listed to identify the fault (the last 2 digits give extra information read by the manufacturer-approved diagnostic system).

NOTE:
When performing voltage or resistance tests, always use a digital multimeter (DMM) accurate to three decimal places, and with an up-to-date calibration certificate. When testing resistance always take the resistance of the DMM leads into account.

NOTE:
Check and rectify basic faults before beginning diagnostic routines involving pinpoint tests.

NOTE:
Inspect connectors for signs of water ingress, and pins for damage and/or corrosion.

NOTE:
If DTCs are recorded and, after performing the pinpoint tests, a fault is not present, an intermittent concern may be the cause. Always check for loose connections and corroded terminals.

Climate Control System
For a complete list of all Diagnostic Trouble Codes (DTCs) that could be logged on this vehicle, please refer to Section 100-00.
For additional information, refer to Diagnostic Trouble Code (DTC) Index - DTC: Heating Ventilation and Air Conditioning Control Module (HVAC)