Temperature Blend Door Actuator(s)
WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
Single-zone EATC systems use one temperature blend door actuator. Dual-zone EATC systems use 2 separate temperature blend door actuators to control 2 separate temperature blend doors for the driver and passenger sides of the vehicle. The temperature blend door actuator(s):
- is/are located on the heater core and evaporator core housing.
- move the temperature blend door(s) on command from the HVAC module.
- each contain 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 doors.
A 5-volt signal is applied to one end of the potentiometer and ground to the other. The voltage available at the wiper indicates the position of the potentiometer. The expressed value of the actuator wiper voltage is sent to the HVAC module and is matched with an expected wiper voltage value. The HVAC module then drives the actuator motor in whichever direction is necessary to make the actuator wiper voltage agree with the expected HVAC module wiper voltage value.