GM Service Manual Online
For 1990-2009 cars only

The heating, cooling, and ventilation for your vehicle can be controlled with this system.

Uplevel shown, Base similar, Hatchback only


Object Number: 1520358  Size: B2

Uplevel shown, Base similar, Sedan only


Object Number: 1738660  Size: B2
Temperature Control: Turn the left knob clockwise or counterclockwise to manually increase or decrease the temperature inside the vehicle. Turn the knob to the blue area for cool air and to the red area for warm air.

(Fan): Turn the middle knob clockwise or counterclockwise to increase or decrease the fan speed. In any setting other than off, the fan will run continuously with the ignition on. The fan must be on in order for the air conditioning compressor to run.

To change the current mode, select one of the following from the right knob:

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

(Bi-Level): This mode directs about half of the air to the instrument panel outlets, and then directs the remaining air to the floor outlets.

(Floor): This mode directs most of the air to the floor outlets. Some of the air will also be directed to the rear outlets. Be sure to keep the area under the front seats clear to allow the flow of air to the rear compartment.

The right knob can also be used to select the defog and defrost modes. Information on defogging and defrosting can be found later in this section.

(Recirculation): This mode keeps outside air from coming into the vehicle. It can be used to prevent outside air and odors from entering the vehicle or to help heat or cool the air inside the vehicle more quickly. If your vehicle has a recirculation button (uplevel model), press the button to turn the recirculation mode on. When the button is pressed, an indicator light in the button comes on. Press the button again to return to outside air mode. If your vehicle has a lever (base model), move the lever to choose the recirculation mode. Using the recirculation mode for extended periods may cause your windows to fog. If this happens, select the defrost mode.

(Outside Air): This mode brings outside air into the vehicle. If your vehicle has a recirculation button (uplevel model), press the button until the recirculation mode is turned off. Your vehicle will then return to outside air mode. If your vehicle has a lever (base model), move the lever to choose the outside air mode.

A/C (Air Conditioning): If your vehicle has air conditioning, follow these steps to use the system. Start the engine and set the fan control knob to the desired speed. The air conditioning compressor does not operate when the fan control knob is in the off position. Press the A/C button to turn the air conditioning compressor on and off. When the A/C button is pressed, an indicator light in the button comes on to show that air conditioning is 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.

For quick cool down on hot days, do the following:

  1. Select the vent mode.
  2. Select the highest fan speed.
  3. Press the A/C button.
  4. Select the recirculation mode.
  5. Select the coolest temperature.

Using these settings together for long periods of time may cause the air inside of the vehicle to become too dry. To prevent this from happening, after the air in the vehicle has cooled, turn the recirculation mode off.

The air conditioning system removes moisture from the air, so a small amount of water might drip underneath the vehicle while idling or after turning off the engine. This is normal.

Defogging and Defrosting

Fog on the inside of windows is a result of high humidity or 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. Use the defog mode to clear the windows of fog or moisture and warm the passengers. Use the defrost mode to remove fog or frost from the windshield more quickly.

For best results, clear all snow and ice from the windshield before defrosting.

Select one of these available modes from the right knob.

(Defog): This mode directs most of the air to the windshield and the floor outlets. A small amount of air is also directed to the outboard outlets for the side windows and to the instrument panel side outlets. When this mode is selected, the system runs the air-conditioning compressor. To defog the windows faster, turn the temperature control knob clockwise to the warmest setting.

(Defrost): This mode directs the air to the windshield and the outboard outlets for the side windows. A small amount of air is also directed to the instrument panel side outlets. When this mode is selected, the system runs the air-conditioning compressor. To defrost the windows faster, turn the temperature control knob clockwise to the warmest setting.

Do not drive the vehicle until all windows are clear.

Rear Window and Outside Mirror Defogger

Your vehicle may have a rear window and outside mirror defogger. This feature only works when the ignition is turned to ON/RUN.

The rear window defogger uses a warming grid to remove fog or frost from the rear window. Before using this feature, clear as much snow from the rear window as possible.

(Rear Window Defogger): Press this button to turn the rear window and outside mirror defogger on or off. An indicator light in the button comes to show that the feature is activated. If your vehicle does not have air conditioning, the rear window defogger will remain on until the button is pressed again or the engine is turned off. If your vehicle has air conditioning, the rear window defogger will turn off about 10 minutes after the button is pressed. The defogger can also be turned off by pressing the button again or by turning the engine off.

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.