GM Service Manual Online
For 1990-2009 cars only

The heating, cooling, and ventilation in your vehicle can be controlled with this system. Your vehicle also has a flow-through ventilation system described later in this section.

Climate Control with Cooled and Heated Seats shown


Object Number: 1689450  Size: B2

Different climate control settings can be selected for the driver and passengers.

Driver's Side Temperature Knob

The driver's side knob is used to adjust the temperature of the air coming through the system on the driver's side. The temperature can be adjusted even if the system is turned off. This is possible since outside air will always flow through the system as the vehicle is moving forward unless it is set to recirculation mode. See "Recirculation" later in this section.

Turn the knob counterclockwise or clockwise to lower or increase the cabin temperature. The display will show the temperature setting decreasing or increasing.

Passenger's Side Temperature Knob

The passenger's side knob can be used to change the temperature of the air coming through the system on the passenger's side of the vehicle. The temperature can be adjusted even if the system is turned off. This is possible since outside air will always flow through the system as the vehicle is moving forward unless it is set to recirculation mode. See "Recirculation" later in this section.

Turn the knob counterclockwise or clockwise to lower or increase the cabin temperature. The display will show the temperature setting decreasing or increasing.

Set the passenger's temperature setting to match the driver's temperature setting by pressing the passenger power knob.

Automatic Operation

AUTO (Automatic): When automatic operation is active the system will control the inside temperature, the air delivery, and the fan speed.

Use the steps below to place the entire system in automatic mode:

  1. Press the AUTO button.
  2. When AUTO is selected, the display will change to show the current temperature(s) and AUTO come on the display. The current delivery mode and fan speed will also be displayed for approximately five seconds.

    When AUTO is selected, the air conditioning operation and air inlet will be automatically controlled. The air conditioning compressor will run when the outside temperature is over about 40°F (4°C). The air inlet will normally be set to outside air. If it is hot outside, the air inlet may automatically switch to recirculate inside air to help quickly cool down the vehicle. The light on the button will come on in recirculation.

  3. Set the driver's and passenger's temperature.
  4. To find your comfort setting, start with a 74°F (23°C) temperature setting and allow about 20 minutes for the system to regulate. Use the driver's or passenger's temperature buttons to adjust the temperature setting as necessary. If you choose the temperature setting of 60°F (15°C), the system will remain at the maximum cooling setting. If you choose the temperature setting of 90°F (32°C), the system will remain at the maximum heat setting. Choosing either maximum setting will not cause the vehicle to heat or cool any faster.

Be careful not to cover the sensor located on the top of the instrument panel near the windshield. This sensor regulates air temperature based on sun load and also turns on the headlamps.

To avoid blowing cold air in cold weather, the system will delay turning on the fan until warm air is available. The length of delay depends on the engine coolant temperature. Pressing the fan switch will override this delay and change the fan to a selected speed.

(Off): Press the driver's side temperature knob to turn off the climate control system. Outside air will still enter the vehicle, and will be directed to the floor. This direction can be changed by pressing the mode button. The temperature can also be adjusted using either temperature knob. Press the up or down arrows on the fan switch, the defrost button, the AUTO button, driver's side temperature knob, or the air conditioning button to turn the system on when it is off.

Manual Operation

The air delivery mode or fan speed can be manually adjusted.

(Fan): The switch with the fan symbol allows the fan speed to be manually adjusted. Press the up arrow to increase fan speed and the down arrow to decrease fan speed. Pressing this button when the system is off will turn the system on. Pressing either arrow while using automatic operation will place the fan in manual operation. The fan setting will display and the AUTO light will turn off. The air delivery will remain in automatic operation.

(Mode): Press this button to manually change the direction of the airflow in the vehicle. Repeatedly press the button until the desired mode appears on the display. When the system is turned off, the display goes blank after displaying the current status of the system.

(Vent): This setting will deliver air to the instrument panel outlets.

(Bi-Level): This mode splits the air between the instrument panel outlets and 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 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 outlets, with some of the air directed to the windshield, side window outlets, and second row floor outlets. In this mode, the system automatically selects Outside Air.

(Defog): See "Defogging and Defrosting" later in this section.

(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 odors from entering the vehicle. Recirculation may also help cool the air inside the 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 blend or defrost mode and increase the fan speed. Recirculation mode can be turned off by pressing the button again, or turning off the engine.

Air Conditioning

(Air Conditioning): Press this button to turn the air conditioning (A/C) compressor on and off. When air conditioning is selected, an indicator light comes on to show that the air conditioning has been activated. Pressing this button when the outside temperature is too cool for air conditioning will make the air conditioning indicator flash three times and then turn off indicating the air conditioning mode is not available. If the air conditioning is on and the outside temperature drops below a temperature which is too cool for air conditioning to be effective, the air conditioning light turns off to show that the air conditioning mode has been canceled.

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

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.

If your vehicle has heated seats or heated and cooled seats, see Heated Seats or Heated and Cooled Seats .

AUX: For vehicles with the rear heating and air conditioning controls. Press the AUX button to turn the rear climate control system on or off. See Rear Air Conditioning and Heating System and Electronic Climate Controls .

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. 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.

Use the mode up and down arrows to select the defog or defrost modes.

(Defog):  This mode directs air to the windshield, floor outlets, and side window vents. When this mode is selected, 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): 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 the 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): The rear window defogger will turn off automatically 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 a razor blade or sharp object to clear the inside rear window. Do not adhere anything to the defogger grid lines in the rear glass. These actions may damage the rear defogger. Repairs would not be covered by your warranty.