Mode actuator
The mode door actuators are reversible, 12-volt direct current (DC) servo motors. The heating-A/C systems on this vehicle use two mode door actuators. One for the panel/floor-air door and one for the defrost-air door.
Both the defrost door actuator (1) and the panel/floor door actuator (2) and the are located on the driver side end of the HVAC housing (3), close to the dash panel.
All actuators (1) are interchangeable with each other. 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 mode door actuators do not require mechanical indexing to the mode-air doors, as they are electronically calibrated by the A/C-heater control.
OPERATION
The mode door actuators are connected to the A/C-heater control through the vehicle electrical system by dedicated two-wire leads and connectors of the HVAC wire harness. The mode door actuators can move the defrost-air door and the panel/floor-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 mode-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the mode-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 mode-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 mode door actuators and the mode-air doors. The A/C-heater control learns the mode-air door stop positions during the Actuator Calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the mode door actuator circuits.
The mode door actuators are diagnosed using a scan tool (Refer to 28 - DTC-Based Diagnostics/HVAC - Diagnosis and Testing).
The mode door actuators cannot be adjusted or repaired and must be replaced if inoperative or damaged.
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