GM Service Manual Online
For 1990-2009 cars only

The automatic A/C system (C68) consists of the following components:

    • A heater
    • A ventilation system
    • An air conditioning system

This system is controlled by electronic circuits and by vacuum circuits. These circuits determine the following locations:

    • The air intake locations
    • The discharge locations

The electronic circuits also control the following items:

    • The mode
    • The A/C compressor clutch operation
    • The blower fan operation
    • The discharge air temperature

The driver may select the following options from the system control panel:

    • A desired interior temperature
    • The blower fan speed
    • The mode of operation

In the automatic mode of operation, the system determines the following settings:

    • The appropriate air intake locations
    • The discharge locations
    • The blower fan speed
    • The discharge air temperature

These settings depend on the temperature and information that is selected by the driver. This information is provided by the system's network of sensors.

The automatic A/C system utilizes a variable displacement orifice tube (VDOT) type of refrigeration system. Refer to Refrigeration System Description .