Air Distribution-Front Control

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

When the mode switch is turned, a signal is sent from the HVAC control module to the mode actuator through the mode door control circuit. When the amplifier circuit receives the signal, the mode door moves into the desired position.

The left instrument panel fuse block provides power to the mode actuator through the ignition 3 voltage circuit. Power and ground are provided to the HVAC control module by the ignition 3 voltage and ground circuits.

A 5-volt reference signal is sent out over the 5-volt reference circuit to the mode actuator. When a desired mode setting is selected, a variable resistor is used to determine the mode door position signals value. That varied 5-volt reference signal is sent back to the HVAC module software inside the module on the mode door position signal circuit. The HVAC module uses this reference voltage to determine the mode actuator position through the mode door position signal circuit. The motor moves the mode door to the desired position. Ground for the mode actuator is provided by the ground circuits and the IP wiring harness junction block.