Operation CHARM: Car repair manuals for everyone.

Air Mix Valve Position

The proper air mix valve position is determined by the heater and A/C programmer. In order to provide the proper mix of warm and cool air, the heater and A/C programmer monitors the following variables:

^ Set temperature.
^ Coolant temperature.
^ Ambient air temperature.
^ Air delivery mode.
^ Inside air temperature.
^ Engine RPM.
^ Low side temperature.
^ Blower speed.
^ Sun load sensor.
^ Mix motor feedback.

Based upon these inputs, the heater and A/C programmer can position the air mix valve for the appropriate blend of air through the evaporator core and heater core depending upon the current program number.