Inspection and Verification

Climate Control System

Inspection and Verification

1. Verify the customer's concern by operating the climate control system to duplicate the condition.

2. Inspect to determine if one of the following mechanical or electrical concerns apply:

Visual Inspection Chart






3. If the inspection reveals obvious concerns that can be readily identified, repair as necessary.

4. NOTE: Make sure to use the latest scan tool software release.
If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).


5. NOTE: The Vehicle Communication Module (VCM) LED prove-out confirms power and ground from the DLC (Data Link Connector) are provided to the VCM (Vehicle Communication Module).
If the scan tool does not communicate with the VCM (Vehicle Communication Module) :

- check the VCM (Vehicle Communication Module) connection to the vehicle.

- check the scan tool connection to the VCM (Vehicle Communication Module).

- refer to - No Power To The Scan Tool, to diagnose no power to the scan tool.


6. If the scan tool does not communicate with the vehicle:
- verify the ignition key is in the ON position.

- verify the scan tool operation with a known good vehicle.

- refer to Information Bus to diagnose no response from the PCM, HVAC module.


7. Carry out the network test.
- If the scan tool responds with no communication from one or more modules, refer to Information Bus.

- If the network test passes, retrieve and record the Continuous Memory Diagnostic Trouble Codes (CMDTCs).


8. Clear the continuous DTCs and carry out the self-test diagnostics from the PCM or HVAC module.

9. NOTE: Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retrieved, diagnose those first. Refer to the PCM DTC Chart. PCM DTC Chart

If the HVAC DTCs retrieved are related to the concern, go to the HVAC Module DTC Chart. If the PCM DTCs retrieved are related to the concern, go to the PCM DTC Chart. For all other DTCs, refer to Body Control Systems. HVAC Module DTC Chart PCM DTC Chart

10. If no DTCs related to the concern are retrieved, GO to Symptom Chart- Climate Control Systems or GO to Symptom Chart- NVH. Symptom Chart - Climate Control Systems Symptom Chart - NVH