Avalanche 2500 4WD V8-8.1L VIN G (2003)
Auxiliary HVAC Control Module
The auxiliary HVAC control module is a class 2 device that receives analog inputs from the front HVAC control assembly and class 2 message inputs
from the rear seat audio control module to maintain auxiliary air temperature and auxiliary air distribution settings. 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, all auxiliary HVAC
DTCs and settings will be erased from KAM. The auxiliary HVAC control module will perform a recalibration of the electric actuators when
commanded with a scan tool or if KAM is lost. This will ensure the actuators are moving with in the calibrated range.
Rear Seat Audio Control Module
The rear seat audio control module is a class 2 device that interfaces between the rear seat passengers and the auxiliary HVAC control module. The
battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). Air temperature, blower motor and air
delivery rocker type switches are located on the face of the module. Pressing a switch enables the module to send a class 2 serial data message to the
auxiliary HVAC control module for the change request. The module does not store auxiliary HVAC DTCs.
Front Auxiliary HVAC Control Assembly
The front auxiliary HVAC control assembly is a non-class 2 device that interfaces between the front seat occupants and the auxiliary HVAC control
module. A 5-volt reference is supplied to the control assembly by the auxiliary HVAC control module. The control assembly varies the 5-volt
reference through three integrated potentiometers to control auxiliary mode door position, auxiliary air temperature door position and auxiliary blower
motor speed inputs to the auxiliary HVAC control module.
