9-7X L6-4.2L (2008)
Air Door Actuator / Motor: Description and Operation
Air Temperature
AIR TEMPERATURE ACTUATOR
The air temperature actuators are a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference,
control, 5-volt reference, and position signal circuits enable the actuator to operate. The control circuit uses either a 0, 2.5, or 5-volt signal to command
the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5-volt control signal commands the actuator movement
in opposite directions. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts.
The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count
range. When the module sets a commanded, or targeted, value, the control signal is changed to either 0 or 5 volts depending upon the direction that the
actuator needs to rotate to reach the commanded value. As the actuator shaft rotates, the changing position signal is sent to the module. Once the position
signal and the commanded value are the same, the module changes the control signal to 2.5 volts.
