Theory Of Operation

The Mode, Temperature, and Recirculation or Blend Doors are opened and closed with electric actuators that provide a position signal. There are five circuits that run between each actuator and the HVAC Module:

• 5-Volt Supply
• Position Signal
• Sensor Ground
• 12-Volt Driver Circuit 1
• 12-Volt Driver Circuit 2

The position signal is used by the HVAC module to monitor the door position. If the desired positions cannot be reached during normal operation, a DTC will set. All of the circuits are also monitored, either directly or indirectly, for open/short circuit faults.