GM Service Manual Online
For 1990-2009 cars only

The temperature valve actuator controls the outlet air temperature, following a voltage signal from the temperature knob in the heater and A/C control.

A reversible DC motor operates the temperature valve. The temperature valve determines how much air passes through the heater core and the evaporator core.

When the temperature knob is in the COOL position (fully left), the following conditions occur:

    • Less than 1 volt is supplied to the actuator.
    • The temperature valve moves in order to block the air flow through the heater core. Heating of the system air does not occur.

When the temperature knob is in the WARM position (fully right), the following conditions occur:

    • The battery voltage is supplied to the temperature valve actuator.
    • The temperature valve moves, forcing all of the air to flow through the heater core. Maximum heating of the system occurs.