Commander 4WD V8-4.7L VIN N (2006)
Air Door Actuator / Motor: Description and Operation
Front Blend Door Actuator
ACTUATOR-BLEND DOOR
DESCRIPTION
The blend door actuators (1) are reversible, 12 volt direct current (DC), servo motors. Models equipped with the MTC single zone heating-A/C system
have a single blend-air door, which is controlled by a single blend door actuator. Models with the ATC dual zone heating-A/C system have two blend-air
doors, which are controlled by two blend door actuators.
The blend door actuator for the single zone heating-A/C system is located on the driver side end of the HVAC air distribution housing, close to the dash
panel.
For the dual zone heating-A/C system, the same blend door actuator used for the single zone system becomes the driver side blend door actuator, which
is mechanically connected to only the driver side blend-air door. A second separate blend door actuator is also located on the passenger side of the
HVAC air distribution housing which is mechanically connected to only the passenger side blend-air door.
The blend door actuators are interchangeable with each other, as well as with the actuators for the mode-air door and the recirculation-air door. Each
actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle (2). Each actuator also has an identical
output shaft with splines (3) that connects it to its respective door linkage and three integral mounting tabs (4) that allow the actuator to be secured to the
HVAC housing. The blend door actuators do not require mechanical indexing to the blend-air doors, as they are electronically calibrated by the
A/C-heater control.
OPERATION
The blend door actuators are 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(s) can move the blend-air door(s) 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(s) 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 actuators and the blend-air
doors. The A/C-heater control learns the blend-air doors stop positions during the 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(s) cannot be adjusted or repaired and, if faulty or damaged, they must be replaced.
