Mode Door Actuator: Operation

The mode door actuator is connected to the heater-A/C control module through the vehicle electrical system by a dedicated two-wire lead and connector from the HVAC wire harness. The mode door actuator can move the mode door in two directions. When the heater-A/C control module pulls the voltage on one side of the motor connection high and the other connection low, the mode door will move in one direction. When the module reverses the polarity of the voltage to the motor, the mode door moves in the opposite direction. When the module makes the voltage to both connections high or both connections low, the mode door stops and will not move. These same motor connections also provide a feedback signal to the heater-A/C control module. This feedback signal allows the module to monitor the operation and relative position of the mode door actuator and the mode door. The heater-A/C control module learns the mode door stop positions during the calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the mode door actuator circuits. The mode door actuator can be diagnosed using a DRBIII(R) scan tool. DIAGNOSIS AND TESTING .