GM Service Manual Online
For 1990-2009 cars only

With these systems, you can control the heating, cooling, and ventilation for your vehicle.

If your vehicle does not have air conditioning, the controls will look like this:

Vehicles Without Air Conditioning


Object Number: 1871359  Size: B1
(Fan): Turn the left knob clockwise or counterclockwise to increase or decrease the fan speed. To increase airflow, turn the knob clockwise. To decrease airflow, turn it counterclockwise. To turn the fan off, turn the mode knob on the far right counterclockwise to the off position.

Temperature Knob: Turn the middle knob located clockwise or counterclockwise to increase or decrease the temperature inside of your vehicle. Turn the knob toward the red area for warmer air. Turn the knob toward the blue area for cooler air.

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

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

(Off): This setting turns the system off.

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

(Bi-Level): This mode directs half of the air to the instrument panel vents, then directs the remaining air to the floor vents. Cooler air is directed to the upper vents and warmer air to the floor vents.

(Floor): This mode directs most of the air to the floor vents. Use this mode to send air to the rear of the vehicle. Keep the area under the front seats free of objects that could obstruct airflow to the rear of the vehicle.

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

If your vehicle has air conditioning, the controls will look like this:

Vehicles With Air Conditioning


Object Number: 829644  Size: B1

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

(Maximum Air Conditioning): Turn the right knob to this setting for maximum cooling. This setting puts the system in recirculation mode and helps to maximize your air conditioner's performance and your vehicle's fuel economy. This setting also cools the air the fastest.

(Air Conditioning): This setting is used for normal cooling on hot days. It cools outside air and directs it through the instrument panel vents.

(Bi-Level Air Conditioning): This setting divides airflow between the floor vents and instrument panel vents. The air conditioning compressor will cycle continuously in this setting as long as the outside temperature is warm enough to activate the compressor.

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

(Floor): This mode directs most of the air to the floor vents. Use this mode to send air to the rear of the vehicle. Keep the area under the front seats free of objects that could obstruct airflow to the rear of the vehicle.

Defogging and Defrosting

Fog on the inside of windows is a result of high humidity (moisture) condensing on the cool window glass. This can be minimized if the climate control is used properly. There are two modes to clear fog or frost from your windshield and side windows.

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.

Turn the mode knob on the right of the climate control panel to select the defog or defrost mode.

(Defog): With this setting, the outside air comes out of both the floor and defroster outlets. Adjust the temperature knob for warmer or cooler air. The air conditioning compressor may operate in this setting to dehumidify the air.

(Defrost): This setting operates the defroster. Most of the air comes out near the windshield, with some going to the floor outlets and front side windows. The air conditioning compressor may operate in this setting to dehumidify the air.

The defog setting is useful for cold weather with a large number of passengers or very humid conditions to help keep the windshield clear. Use defrost to remove fog or ice from the windshield quickly in extremely cold conditions. The temperature knob should be in the red area and the fan control toward high. Do not drive the vehicle until all the windows are clear.

Rear Window Defogger

For vehicles with a rear window defogger, a warming grid is used to remove fog or frost from the rear window.

Be sure to clear as much snow from the rear window as possible.


Object Number: 829690  Size: A1

Press this button located near the fan control to turn the rear window defogger on or off.

An indicator light in the button comes on when the rear window defogger is working.

The rear window defogger will only work when the ignition is in RUN.

The rear window defogger turns off several minutes after the button is pressed. The defogger can also be turned off by pressing the button again or by turning off the engine.

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.