Malibu V6-3.5L VIN 8 (2004)
Control Module HVAC: Description and Operation
HVAC SYSTEM - MANUAL
AIR DELIVERY
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 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 features as shown in the table.
HVAC SYSTEM - AUTOMATIC
HVAC CONTROL MODULE
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 ignition 3
voltage circuit provides a device on signal. The control module supports the features as shown in the table.
BLOWER MOTOR CONTROL PROCESSOR
The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery
positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a pulse width modulation (PWM)
signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower
motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.
