GM Service Manual Online
For 1990-2009 cars only

With this system you can control the heating, cooling, defrost, defog and ventilation of your vehicle.


Object Number: 1700473  Size: B2

Manual Operation

Turn the right knob clockwise or counterclockwise to direct the airflow inside of your vehicle.

To change the current mode, select one of the following:

(Vent):  This mode directs air to the instrument panel outlets.

(Bi-Level):  This mode directs half of the air to the instrument panel outlets and to the floor outlets. The flow can be divided between vent and floor outlets depending upon where the knob is placed between the settings. A little air is directed towards the windshield and side window outlets. Cooler air is directed to the upper outlets and warmer air to the floor outlets.

(Floor): This mode directs most of the air to the floor outlets, with some of the air directed to the windshield, side window outlets, and second row floor outlets. In this mode, the system will automatically select outside air. Recirculation cannot be selected when in Floor Mode.

The right knob can also be used to select defog or defrost mode. For more information, see "Defogging and Defrosting" later in this section.

By positioning the right knob between two modes, a combination of those two modes is selected.

The air conditioning compressor will be on unless the outside temperature is close to freezing.

(Fan):  Turn the left knob clockwise or counterclockwise to increase or decrease the fan speed. Turn the knob all the way counterclockwise to turn the front system off.

(Recirculation): Press this button to turn the recirculation mode on. When the button is pressed, an indicator light will come on. This mode keeps outside air from entering the vehicle. It can be used to reduce outside air and prevent odors from entering your vehicle. Recirculation may also help cool the air inside your vehicle more quickly once the temperature inside the vehicle is less than the outside temperature. The recirculation mode cannot be used with floor, defrost, or defogging modes. If you try to select recirculation in one of those modes, the indicator will flash three times and turn off. The air conditioning compressor will also come on when this mode is activated. While in recirculation mode the windows may fog when the weather is cold and damp. To clear the fog, select either the defog or defrost mode and increase the fan speed. Recirculation mode can be turned off by pressing the button again, or turning off the engine.

AUX (Auxiliary): Pressing this button will turn the rear heating and air conditioning on. See Rear Air Conditioning and Heating System or Rear Air Conditioning and Heating System and Electronic Climate Controls for more information.

Temperature Control:  Rotate the thumbwheels up or down to increase or decrease the temperature on the driver's side or the passenger side of the vehicle for the dual zone system.

(Air Conditioning):  Press this button on the left knob to turn the air conditioning system on or off. When A/C is pressed, an indicator light will come on to let you know that the air conditioning has been activated.

On hot days, open the windows to let hot inside air escape; then close them. This helps to reduce the time it takes for your vehicle to cool down. It also helps the system to operate more efficiently.

The air conditioning system removes moisture from the air, so you may sometimes notice a small amount of water dripping underneath your vehicle while idling or after turning off the engine. This is normal.

Defogging and Defrosting

Fog on the inside of the windows is a result of high humidity (moisture) condensing on the cool window glass. This can be minimized if the climate control system is used properly. There are two modes to clear fog or frost from your windshield. Turn the right knob clockwise to select the defog or defrost mode.

(Defog):  The defog mode is used to clear the windows of fog or moisture and warm the passengers. This mode directs air to the windshield, floor outlets, and side window vents. When you select this mode, the system turns off recirculation and runs the air conditioning compressor unless the outside temperature is close to freezing. The recirculation mode cannot be selected while in the defog mode. Do not drive the vehicle until all the windows are clear.

(Defrost): The defrost mode is used to remove fog or frost from the windshield more quickly. This mode directs a portion of the air to the windshield and side window vents and some to the floor vents. In this mode, the system will automatically force outside air into your vehicle. The recirculation mode cannot be selected while in the defrost mode. The air conditioning compressor will run automatically in this setting, unless the outside temperature is close to freezing. Do not drive the vehicle until all the windows are clear.

Rear Window Defogger

The rear window defogger uses a warming grid to remove fog from the rear window.

(Rear Window Defogger): Press this button on the right knob to turn on the rear window defogger. The system will automatically turn off several minutes after it has been activated. The defogger can also be turned off by pressing the button again or by turning off the engine. Do not drive the vehicle until all the windows are clear.

If your vehicle has heated outside rearview mirrors, the mirrors will heat to help clear fog or frost from the surface of the mirror when the rear window defog button is pressed.

Notice: Do not use anything sharp on the inside of the rear window. If you do, you could cut or damage the warming grid, and the repairs would not be covered by the vehicle warranty. Do not attach a temporary vehicle license, tape, a decal or anything similar to the defogger grid.