Auxiliary HVAC Control Module

WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

The auxiliary HVAC control module is a GMLAN device that interfaces between the operator, the front HVAC control module, and the auxiliary HVAC system to maintain air temperature and air distribution settings. Battery power, ground, and LED dimming are supplied to the auxiliary HVAC control module. The front HVAC control module monitors the position of the rear air temperature actuator and the auxiliary mode actuator. The front HVAC module will move the actuators to the proper position when it receives a request from the auxiliary HVAC control module on which position to place the actuator. The auxiliary HVAC control module is powered ON or OFF through GMLAN communication of vehicle power-mode.

The auxiliary HVAC control module can be turned ON and OFF by pressing the AUX button on the front HVAC control module. The rear control can also be turned ON by pressing any rocker button on the control head. Pressing the fan blower rocker button down will eventually turn off the control head. When the front climate control system is turned off or in defrost mode, the rear climate control system is turned off. The rear system will turn back on once another front mode is selected.