Liberty 2WD V6-3.7L (2008)
Air Door Actuator / Motor: Description and Operation
Blend Door Actuator
Description
DESCRIPTION
The heating-A/C system uses a reversible, 12-volt direct current (DC) servo motor which mechanically positions the blend-air door. The blend door
actuator (1) is located on the driver side of the HVAC housing.
The blend door actuator is interchangeable with the actuators for the mode-air doors and the recirculation-air door. Each actuator is contained within a
black molded plastic housing with an integral wire connector receptacle (2) and integral mounting tabs (3) that allow the actuator to be secured to the
HVAC housing. The blend door actuator output shaft (4) is connected to the linkage that drives the blend-air door. The blend door actuator does not
require mechanical indexing to the blend-air door, as it is electronically calibrated by the A/C-heater control.
Operation
OPERATION
The blend door actuator is connected to the A/C-heater control through the vehicle electrical system by a dedicated two-wire lead and connector of the
HVAC wire harness. The blend door actuator can move the blend-air door in two directions. When the A/C-heater control pulls the voltage on one side
of the motor connection high and the other connection low, the blend-air door will move in one direction. When the A/C-heater control reverses the
polarity of the voltage to the motor, the blend-air door moves in the opposite direction. When the A/C-heater control makes the voltage to both
connections high or both connections low, the blend-air door stops and will not move.
The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the blend door actuator and the blend-air
door. The A/C-heater control learns the blend-air door stop positions during the actuator calibration procedure and will store a diagnostic trouble code
(DTC) for any problems it detects in the blend door actuator circuits.
The blend door actuator cannot be adjusted or repaired and must be replaced if found inoperative or damaged.
