CKT 141 (BRN) powers the temperature actuator motor when the ignition switch is in the RUN position. CKT 150 grounds the motor to Ground G200. CKT 141 (BRN) powers the HVAC control module when the ignition switch is in the RUN position. CKT 150 (BLK) grounds the HVAC control module to Ground G200.

The temperature actuator door is positioned in proportion to the variable voltage signal received from the HVAC control module. Adjusting the temperature dial at the HVAC control module adjusts a rheostat. The rheostat provides a voltage signal proportional to the dial position. CKT 733 (LT BLU) carries this voltage to the temperature actuator motor. The temperature actuator motor then positions the door in response to the voltage signal.