Expedition 2WD V8-281 4.6L SOHC (1998)
Air Door Actuator / Motor: Description and Operation
The A/C electric blend door actuator is located on the plenum assembly.
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Its function is to move the air temperature blend door on command from the control assembly.
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The A/C electric blend door actuator 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 air temperature blend door.
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A 5 volt signal is applied to the ends 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 Electronic Automatic Temperature Control (EATC) module and is compared to the
desired wiper voltage determined by the EATC module. The control module then drives the actuator motor in whichever direction is necessary to
make the actuator wiper voltage agree with the desired wiper voltage.
