GM Service Manual Online
For 1990-2009 cars only

This vehicle may have a dual or single climate control system. The heating, cooling, defrost, defog and ventilation can be controlled with this system. For vehicles with heated seats, see Heated Seats .

Dual Zone with Optional Heated Seat Controls


Object Number: 1542656  Size: B2

Single Zone


Object Number: 1585484  Size: B2

Manual Operation

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

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

(Vent):  Air is directed to the instrument panel outlets.

(Bi-Level):  Air is divided between the instrument panel outlets and the floor outlets.

(Floor): Air is directed to the floor outlets, with some of the air directed to the windshield and side window outlets. In this mode, the system automatically selects outside air.

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 operate unless the outside temperature is 40°F (4°C) or below.

(Fan):  Turn the left knob clockwise or counterclockwise to increase or decrease the fan speed. If the airflow seems low when the fan is at the highest setting, the passenger compartment air filter may need to be replaced. There will be some airflow noticeable from the various outlets when driving, even with the fan in the off position. For more information, see Passenger Compartment Air Filter and Scheduled Maintenance .

(Outside Air):  Press to turn on outside air. An indicator light comes on to show that it is activated. When this mode is on, outside air will circulate throughout the vehicle.

(Recirculation): Press to turn on the recirculation mode. An indicator light comes on to show that it is activated. This mode keeps outside air from entering the vehicle. It can be used to prevent outside air and odors from entering the vehicle. Recirculation may also help heat or cool the air inside the vehicle more quickly once the temperature inside the vehicle is equal to or better than the outside temperature. The recirculation mode is not available in outside air, floor, defog or defrost modes. If the button is selected while in these modes, the indicator will flash three times.

Temperature Control:  Turn 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. Turn the center knob clockwise or counterclockwise to increase or decrease the temperature for the single zone system.

For quick warm up on cool days, do the following:

  1. Select the warmest temperatures for both zones.
  2. Select the mode.
  3. Select a medium speed.
  4. When the air starts to feel warm, turn the fan knob to the highest speed.
(Air Conditioning):  Press to turn the air conditioning system on or off. An indicator light comes on to show that it is activated. The air conditioning can be selected in any mode as long as the fan is on and the outside temperature is above freezing. A flashing indicator light indicates that the air conditioning compressor is currently not available.

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.

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

  1. Select the mode.
  2. Press the button.
  3. Select the coolest temperature for both zones.
  4. Select the highest speed.
  5. When the coolest temperature is selected in the A/C mode, the system automatically goes into the recirculation mode to improve cooling. Press the Outside Air or Recirculation button to turn off the automatic recirculation. This feature stays off until the climate control system is powered on again or the vehicle has been turned off and on again.

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

The air conditioning system removes moisture from the air, so a small amount of water may drip under the 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 the 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.

Do not drive the vehicle until all the windows are clear.

Turn the right knob clockwise to select the defog or defrost mode.

(Defog):  Air is directed equally to the windshield and the floor outlets. When defog is selected, the system turns off recirculation and runs the air conditioning compressor unless the outside temperature is below 40°F (4°C).

(Defrost): Air is directed to the windshield with some air to the side window vents and the floor vents. When defrost is selected, the system automatically forces outside air into the vehicle. The air conditioning compressor will run automatically in this setting, unless the outside temperature is below 40°F (4°C).

Rear Window Defogger

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

(Rear Window Defogger): The rear window defogger turns off automatically after it has been activated for 10 minutes. It can be turned off manually, by pressing the button again or by turning the ignition to the LOCK/OFF position. If additional window clearing is required, the rear window defogger can be turned on again for additional window clearing. The length of defogger operation will increase if the vehicle is being driven.

For vehicles with 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. See Outside Power Mirrors .

Do not drive the vehicle until all the windows are clear.

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.