Theory Of Operation

After the initial installation of the A/C Heater Control, the controller is calibrated to each individual blend/mode door actuator. The actuators are connected to the A/C Heater Control by a dedicated five-wire sensor and control circuits. The actuator can move the blend/mode-air doors in two directions. When the A/C Heater Control pulls the voltage on one side of the control circuit high and the other low, the door actuator will move in one direction. When the A/C Heater Control reverses the polarity of the voltage to the motor, the blend door actuator moves in the opposite direction. Once the A/C Heater Control makes the voltage to both control circuits high or low, the door actuator will stop its movement and stay in that position. The blend/mode door actuator contains a three wire potentiometer, which the A/C Heater Control uses to monitor the relative position of the blend/mode air doors. The A/C Heater Control learns the blend-air door stop positions during the calibration procedure.