With Electronic Automatic Temperature Control (EATC)

TEMPERATURE BLEND DOOR ACTUATOR

The EATC system utilizes a temperature blend door actuator to control the temperature blend door. The temperature blend door actuator:
- is located on the plenum chamber.
- moves the temperature blend door on command from the EATC module.
- contains a reversible electric motor and a potentiometer. The potentiometer wiper is connected to the actuator output shaft and moves with the output shaft to indicate the position of the temperature blend door.
- receives a reference voltage to one end of the potentiometer. The voltage available at the wiper indicates the position of the potentiometer. The expressed value of the actuator wiper voltage is sent to the EATC module and is matched with an expected wiper voltage value. The EATC module then drives the actuator motor in whichever direction is necessary to make the actuator wiper voltage match the expected EATC module wiper voltage value.

VACUUM CONTROL MOTORS

The three vacuum control motors have the following characteristics:
- They are actuated by the ATC solenoid and manifold based on input from the EATC module.
- They position the mode doors to direct system airflow to the vehicle interior as determined by the EATC module settings.
- The air inlet door vacuum control motor is a single-diaphragm actuator with a single vacuum source.
- The airflow mode door vacuum control motors are double-diaphragm actuators with two separate vacuum sources to allow the actuator to fully retract or partially retract.
- When vacuum is applied to both vacuum sources, the actuator will fully retract.
- When vacuum is applied only to the partial stage vacuum source, the actuator will partially retract.