GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 DeVille 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 HVAC Temperature Controls Circuit Description

Air Mix Valve Linkage

The air mix valve linkage consists of a plastic crank arm which works with the following components:

    • The output shaft of the actuator
    • A nylon retainer
    • A rod

One end of the rod is fastened to the air mix valve. The opposite end is retained by the nylon retainer.

The heater and A/C programmer uses the actuators in order to drive the air mix valves.

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:

    • The set temperature
    • The coolant temperature
    • The ambient air temperature
    • The air delivery mode
    • The inside air temperature
    • The engine revolutions per minute (RPM)
    • The low side temperature
    • The blower speed
    • The sun load sensor
    • The mix motor feedback

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