GM Service Manual Online
For 1990-2009 cars only

The heating, cooling, and ventilation of the vehicle can be controlled with this system.


Object Number: 2051399  Size: B2
  1. Temperature Control

  2. Fan Control

  3. Air Delivery Mode Control

  4. Air Conditioning

  5. Recirculation

  6. Rear Window Defogger

(Off): Turn the fan control to this position to turn the fan off.

Temperature Control: Turn clockwise or counterclockwise to increase or decrease the temperature.

(Fan Control): Turn clockwise or counterclockwise to increase or decrease the fan speed.

Air Delivery Mode Control: Turn clockwise or counterclockwise to change the direction of the airflow inside the vehicle. The control can be set between two modes to get a combination of the modes. Select from the following modes:

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

(Bi-Level): Air is directed to the instrument panel, floor, defroster and side window outlets. Cooler air is directed to the upper outlets and warmer air to the floor outlets.

(Floor): Air is directed to the floor outlets, with some directed to the side window and defroster outlets. If low or no airflow is on the passenger side, make sure that the carpet covering is tucked under floor outlets.

(Floor/Defog): This mode clears the windows of fog or moisture. Air is directed to the windshield, side window, and floor outlets. In this mode, the system runs the air conditioning compressor unless the outside temperature is near freezing or below.

(Defrost): This mode removes fog or frost from the windshield more quickly. Air is directed to the windshield and side window outlets. In this mode, the system runs the air conditioning compressor unless the outside temperature is near or below freezing. Do not drive the vehicle until all the windows are clear. To prevent fogging on the inside of the windows in modes other than floor/defog and defrost, make sure the air conditioning compressor is on and recirculation mode is off.

(Air Conditioning) : Press to turn the air conditioning system on or off. An indicator light comes on to show that the air conditioning is on. This setting cools and dehumidifies the air entering the vehicle. The air conditioning does not work if the fan is turned off. If air conditioning is selected with fan off, the indicator light flashes three times and then turns off. There could be a slight change in engine performance when the air conditioning compressor turns off and turns on again. This is normal. The system is designed to make adjustments to help with fuel economy while still maintaining the selected temperature. Air conditioning does not operate at temperatures below 40°F (4°C). In temperatures above 40°F (4°C) , the air conditioning cannot be turned off in defrost, floor/defog, and recirculation modes because it helps to remove moisture from the vehicle. It also helps to keep the windows clear. On hot days, open the windows to let the hot inside air escape; then close them. This helps 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 .
  2. Select .
  3. Select the air conditioning to on.
  4. Select the coolest temperature.
  5. Select the highest fan speed.

Using these settings together for long periods of time can 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 under the vehicle while idling or after turning off the engine. This is normal.

(Recirculation): Press to turn the recirculation mode on or off. An indicator light comes on to show that recirculation is on. This mode recirculates and helps to quickly cool the air inside the vehicle. It can be used to help prevent outside air and odors from entering the vehicle. Recirculation is available in the bi-level and vent modes. If recirculation is selected in either floor/heat, floor/defog, or defrost mode, the indicator light flashes three times indicating it is not available in that mode.

Rear Window Defogger

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

(Rear Defogger): Press to turn the rear window defogger on or off. An indicator light comes on to show that the rear window defogger is on. Be sure to clear as much snow from the rear window as possible. The rear window defogger turns off about fifteen minutes after the knob is pressed. If turned on again, the defogger runs for about seven and one-half minutes before turning off. If vehicle speed is greater than 50 mph (80 kph) and the rear defogger is active, it remains on as long as the speed is greater than 50 mph (80 kph). The defogger can also be turned off by turning off the engine. Do not use the rear defogger when the convertible top is down.

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.