ACTUATOR-BLEND DOOR

The rear blend door actuator (1) is a reversible, 12 volt direct current (DC), servo motor. The rear blend door actuator is located on the back of the rear HVAC housing. The rear blend door actuator is interchangeable with the actuator for the mode-air door. Each actuator is contained within an identical molded plastic housing with an integral wire connector receptacle (2). Three integral mounting tabs (4) allow the actuator to be secured to the rear HVAC housing. Each actuator also has an identical output shaft with splines (3) that connects it to the rear air door. The rear blend door actuator does require mechanical indexing to the rear blend-air door, as it is electronically calibrated by the A/C-heater control.

OPERATION

The rear 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 rear HVAC wire harness. The rear blend door actuator can move the rear 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 rear blend-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the rear 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 rear 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 rear blend door actuator and the rear blend-air door. The A/C-heater control learns the rear blend-air door stop positions during the calibration procedure and will store a diagnostic trouble code (DTC) for any problems it detects in the rear blend door actuator circuit.