Air Distribution: Notes

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

When the mode switch is pressed, a ground is provided from the HVAC control module to the mode actuator through the mode door control circuits. When the mode actuator receives the signal, the mode actuator moves into the desired position.

The HVAC control module provides power and ground to the mode actuator. The HVAC control module receives power from the rear fuse block through the ignition 3 voltage circuit. Ground is provided by the ground circuit.

The mode actuator is a reverse polarity motor. Each circuit provides both power and ground to the mode actuator. When the mode actuator is being held in position, both of the mode door control circuits have 12 volts applied to both sides of the actuator motor. This holds the actuator stationary. When a mode is requested, one of the mode door control circuits will ground, driving the mode actuator into the desired mode.