GM Service Manual Online
For 1990-2009 cars only

The dual zone A/C system performs the following functions:

    • Heating
    • Ventilation
    • Air conditioning

The dual zone A/C system is controlled by vacuum and electronic circuits. Both electronic and vacuum circuits determine air intake and discharge locations. Electronic circuits also control the following functions:

    • Mode operation
    • A/C compressor clutch operation
    • Fan operation
    • Discharge air temperature

The driver may select any of the following functions from the front HVAC control assembly:

    • Front interior temperature
    • Fan speed
    • One of eight different modes of operation for the front seating area

The passenger may select any of the following functions from the rear HVAC control assembly:

    • Rear interior temperature
    • Fan speed
    • One of five different modes of operation for the rear seating area

The system determines these conditions from the following information:

    • The temperature that is selected by the driver or the rear passenger (s)
    • The mode position that is selected by the driver or the rear passenger (s)
    • Any information that is provided by the system's network of sensors

For more information on the front HVAC control assembly operation. Refer to Control Assembly Description .

For more information on the rear HVAC control assembly operation. Refer to Control Assembly Description .