HVAC Control Module: Notes

WARNING: This page is about a different car, the 2003 Chevrolet SSR. However, it is still accessible from the selected car via links, so may be relevant.

The HVAC control module is a non-class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provide power to the control module. The ignition 3 voltage circuit provides a device on signal to the HVAC control module. The control module supports the following features:

Air Temperature Description and Operation

Feature	Availability
Afterblow	No
Purge	No
Personalization	No
Actuator Calibration	Yes

Upon initial ignition ON after a battery disconnect the HVAC control module will calibrate the air temperature and mode actuators. The next ignition cycle the HVAC control module takes the follow actions:

The HVAC control module will first perform required memory diagnostics. If there is fault, then A/C request will be disabled and the recirculation door position will be defaulted to outside air position
Restore the A/C state from memory
Restore the recirculation actuator position from memory
Set the rear defrost output to OFF
Set the blower motor speed to the actual blower motor switch position
Set the mode door position to the actual mode switch position
Set the air temperature door position to the actual air temperature switch position

Diagnostic trouble codes (DTC) are manually retrieved and cleared through the HVAC control module. Refer to Diagnostic Trouble Code (DTC) Displaying or Diagnostic Trouble Code (DTC) Clearing .