Circuit/System Description
WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
The actuators used for the HVAC system are stepper motors controlled via serial data. The BCM supplies a B+ voltage to the actuators, and ground is provided by the wiring harness. The BCM sends a LIN serial data message to request the actuator to move to the calculated position to achieve the desired setting.