Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
HVAC Control Module
The HVAC control module is a non-GMLAN device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive and ignition 3 voltage circuits provide power to the control module. The HVAC control module during defrost mode will change the A/C compressor LED status from on to off. The control head displays recirc, outside air, A/C and rear defrost feedback status through LED indicators. The control head has a rear defrost request switch please refer to Rear Window Defogger Description and Operation in Stationary Windows for operation. The HVAC control head will display NO COMMUNICATION when checking DTCs or doing a vehicle diagnostic system check refer to Diagnostic Trouble Code (DTC) List - Vehicle and Diagnostic System Check - Vehicle in Vehicle DTC Information. The control module supports the following features:
| Feature | Availability |
|---|---|
| Afterblow | Dealer turn on feature |
| Purge | Yes |
| Personalization | No |
| Actuator Calibration | Yes |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.