Door Actuators

WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.

The actuators are 2-wire, bi-directional electric motors that share the same common control circuit. When the operator adjusts the actuators, the control module can only operate one actuator at a time due to the shared common control circuit.

The actuator control priority sequence when the MODE is set to VENT or RECIRC or BI-LEVEL from other modes shall be:

Mode Actuator
Defrost Actuator
Left Temperature Actuator
Right Temperature Actuator
Recirculation Actuator
Auxiliary Mode Actuator
Auxiliary Temperature Actuator

The actuator control priority sequence when the MODE is set to HEATER, DEFOG or DEFROST from other modes shall be:

Recirculation Actuator
Mode Actuator
Defrost Actuator
Left Temperature Actuator
Right Temperature Actuator
Auxiliary Mode Actuator
Auxiliary Temperature Actuator

The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. The HVAC control module reverses the polarity of the circuits to move the actuator in the opposite direction. The HVAC control module determines the door position by counting motor pulses on one of the control circuits. These pulses are small voltage fluctuations that occur when the brush is shorted across 2 commutator contacts as the motor rotates. As the actuator shaft rotates, the HVAC control module monitors the voltage drop across an internal resistance to detect the pulses. The HVAC control module converts the pulses to counts with a range of 0-255 counts. The HVAC control module uses a range of 0-255 counts to index the actuator position.