Theory Of Operation-HVAC Actuators

The HVAC door actuators are bi-directional 12v motors controlled by the HVAC Module. The HVAC module will change polarity of the two 12v driver circuits to meet the requested door position.

The actuators each contain a potentiometer which provides the HVAC door position to the HVAC Module. The HVAC module provides the potentiometer with a 5-volt supply, sensor ground and signal circuit. The signal circuit provides the HVAC module with an analog voltage that varies within a 0-5 volt range depending on the position of the HVAC door.

5-wire actuator circuits:

• 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. The actuator circuits are monitored, either directly or indirectly, for open/short circuit faults.