Control Module HVAC: Testing and Inspection

The control switch and timer circuit may be tested in the vehicle with or without scan tool (DRB).

TESTING WITH SCAN TOOL
If using the scan tool, refer to the proper Body Diagnostic Procedures.

TESTING WITHOUT SCAN TOOL

HVAC Control Module Connectors:

1. Remove the control switch from console and do not disconnect control switch.

Control Module Test:

2. Using a ohmmeter, check leads between Pins 5 and 8 of the 8-way connector. Depress the rear window defogger button and the resistance reading should be 500 to 520 ohms. If not OK, replace HVAC. If OK, check:
- Rear window relay (EBL)
- Blown fuse
- Cut wire
- Poor ground
- Poor connection
- Defective BCM
- Bulkhead connector inoperative