Econoline E550 V10-6.8L VIN S (2003)
Control Assembly: Description and Operation
Main Climate Control
The climate control assembly has three system controls:
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The A/C heater function selector switch combines a vacuum selector valve with two electrical switches to supply battery positive voltage to the
A/C clutch circuit and the blower motor control circuit.
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The temperature selection is accomplished with a potentiometer connected to the electric blend door actuator that controls positioning of the
temperature blend door. Movement of the control knob from COOL (Blue) to WARM (Red) causes a corresponding movement on the air
temperature control door and determines the temperature that the system will maintain.
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The blower motor switch controls blower motor speed by adding or bypassing resistors in the heater blower motor switch resistor.
