Air Distribution-Automatic Auxiliary HVAC Control

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Depending upon the auxiliary HVAC system content, the auxiliary mode actuator can be controlled by either of the auxiliary HVAC controls. The primary HVAC control module located in the dash does not control the auxiliary HVAC system. If the vehicle does not have a sunroof (CF5), then the front auxiliary controls must be set to the rear position for the rear auxiliary controls to operate. The vehicle operator determines the mode setting by placing a mode switch in a desired speed position. Only upper and lower vent positions are available in the rear of the vehicle.

When a mode position is selected on either of the auxiliary HVAC controls, a signal is sent from the auxiliary HVAC controls to the auxiliary mode actuator through the mode door control circuit. The auxiliary mode actuator moves the auxiliary mode door to the desired position. When the auxiliary mode door moves to a desired position, a variable resistor within the actuator is used to create the mode door position signal. The HVAC module uses the mode door position signal to determine the actual auxiliary mode door position. Power and ground are provided to the HVAC control module by the fuse block through the ignition 3 voltage circuit and the ground circuits through the right instrument panel junction block. A 5 volt reference signal is sent to the actuator through the 5 volt reference circuit, through the right instrument panel junction block, to the auxiliary mode actuator.