Theory Of Operation-HVAC Actuators

The Rear Door Actuators are LIN Bus controlled electric actuators that provide position signal to the HVAC Module. There are either three or four circuits that connect each actuator toe the HVAC Module.

4-wire actuator circuits:

• Power Supply
• Ground
• LIN Bus (IN)
• LIN Bus (OUT)

3-wire actuator circuits:

• Power Supply
• Ground
• LIN Bus

The LIN Bus circuit is wired in series (daisy chained) passing through and connecting each actuator to the HVAC Module. The LIN signal is used by the HVAC Module to control and 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.