Operation CHARM: Car repair manuals for everyone.
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Air Temperature Actuator

When a desired temperature setting is selected, a variable resistor is used to determine the air temperature actuator position signals value. The resistor changes the 12-volt signal coming into the actuator and varies the voltage to move the actuator into the proper position, based on the signal from the HVAC control assembly. The motor opens the air temperature actuator to a position to divert sufficient air past the heater core to achieve the desired vehicle temperature. Ground is provided by the ground circuit.

The instrument panel fuse block provides power to the air temperature actuator through the ignition 3 voltage circuit. Power and ground are provided to the HVAC control assembly by the ignition 3 voltage and ground circuits.