HVAC Control Module Test

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

Testing With The DRBIII(R) Scan Tool
If using the DRBIII(R) scan tool, refer to the proper Body Diagnostic Procedures manual.

Fig.4 HVAC Control Module Connectors:

Testing Without The DRBIII(R) Scan Tool
1. Remove the control switch from console and do not disconnect control switch.
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

Refer to Wiring Diagrams for circuit information.