HVAC Control Module: Notes

The HVAC control module is a GMLAN device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The control module communicates on the low-speed data bus. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, then all HVAC DTCs and settings will be erased from KAM. The temperature display reading at the control head can be converted from °C to °F by pressing the Auto button for a minimum of 3 seconds. The HVAC control module during defrost modes will change the A/C compressor LED status from on to off. The ignition 3 voltage circuit provides a device on signal. The control module supports the following features: