GM Service Manual Online
For 1990-2009 cars only

With this system, you can control the heating, cooling and ventilation in your vehicle.


Object Number: 849607  Size: B2

You can select different climate control settings 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 and an arrow pointing to the driver will be displayed under and to the left of the temperature setting.

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 and an arrow pointing to the passenger will be displayed under and to the right of the temperature setting.

The passenger's temperature setting can be set to match the driver's temperature setting by pressing and holding the AUTO button for four seconds. Both the driver and passenger arrows will be displayed.

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 driver's set temperature, delivery mode and fan speed. Press the AUTO button again within five seconds to display the passenger's set temperature.

    If the driver's and passenger's temperature settings are the same when AUTO is pressed, the temperature setting and both arrows will be displayed for five seconds along with the automatic air delivery mode and fan speed. After the five-second update, the display will change to show the temperature setting, both arrows and AUTO.

    If the driver's and passenger's temperature settings are not the same, the opposite side temperature setting will be displayed for an additional five seconds. To make the passenger's temperature the same as the driver's press and hold the AUTO button for about four 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's hot outside, the air inlet may automatically switch to recirculate inside air to help quickly cool down your vehicle. The light on the button will illuminate 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. Turn the driver's or passenger's side temperature knob 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 your 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 this button to turn off the entire 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, or the air conditioning button to turn the system on when it is off.

Manual Operation

You may manually adjust the air delivery mode or fan speed.

(Fan): The switch with the fan symbol allows you to manually adjust the fan speed. 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.

(Mode): Press this button to manually change the direction of the airflow in your vehicle. Keep pressing the button until the desired mode appears on the display. If you press the mode button to select an air delivery mode, the display will change to show you the selected air mode delivery. The display will then show the current status of the system. When the system is turned off, the display will go blank after displaying the current status of the system.

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

(Bi-Level): This setting will deliver warmer air to the floor and cooler air to the instrument panel outlets.

(Floor): This setting will deliver air to the floor outlets.

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

(Recirculation): Press this button to limit the amount of outside air entering your vehicle. The light on the recirculation button will glow. This is helpful when you are trying to limit odors entering your vehicle and for maximum air conditioning performance in hot weather. Press this button again to allow outside air to enter the vehicle. The light on the recirculation button will go off. Pressing this button also cancels the auto recirculation feature. To resume the auto recirculation function, press the AUTO button. Each time the vehicle is started, the system will revert to the auto recirculation function. If you select recirculation while in defrost, defog or floor, the light in the button will flash and then go out to let you know that this is not allowed. This is normal and helps to prevent fogging. When the weather is cool or damp, operating the system in recirculation for extended periods of time may cause fogging of the vehicle's windows. To clear the fog, select either defog or front defrost. You may also notice that the A/C compressor will run while in recirculation mode. This is normal and helps to prevent fogging.

(Air Conditioning): Press this button to turn the air conditioning (A/C) compressor on and off. The snowflake symbol will appear on the display when the A/C is on and will turn off when the air conditioning is off. Pressing this button when the outside temperature is too cool for air conditioning to be effective will make the snowflake symbol flash three times and then turn off to let you know that 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 snowflake symbol will turn off to let you know that the air conditioning mode has been canceled.

When air conditioning is selected or in AUTO mode, the system will run the air conditioning automatically to cool and dehumidify the air entering the vehicle. If you select A/C off while in front defrost, defog or recirculation, the A/C snowflake symbol will turn off, but the A/C compressor will still run to help prevent fogging.

On hot days, open the windows long enough to let hot inside air escape. This reduces the time it takes for your vehicle to cool down. Then keep your windows closed for the air conditioner to work its best.

On cool, but sunny days while using manual operation of the automatic system, use bi-level to deliver warm air to the floor and cooler air to the instrument panel outlets. To warm or cool the air delivered, turn the temperature knob to the desired setting.

In AUTO mode the system will cool and dehumidify the air inside the vehicle. Also while in AUTO mode, the system will maximize its performance by using recirculation as necessary.

(Off): Press this button to turn off the entire 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, or the air conditioning button to turn the system on when it is off.

Defogging and Defrosting

You can use either defog or front defrost to clear fog or frost from your windshield. Use the defog mode to clear the windows of fog or moisture. Use the front defrost button to defrost the front windshield.

(Defog): Use this setting to clear the windows of fog or moisture. Press the mode button to select this setting. This setting will deliver air to the floor and windshield outlets.

(Defrost): Press this button to defrost the windshield. The system will automatically control the fan speed if you select defrost from AUTO mode. If the outside temperature is 40°F (4°C) or warmer, your air conditioning compressor will automatically run to help dehumidify the air and dry the windshield.

Rear Window Defogger

If your vehicle has this feature, the lines you see on the rear window warm the glass. The rear window defogger uses a warming grid to remove fog from the rear window.

(Rear): Press this button to turn the rear window defogger on or off. An indicator light in the button will come on to let you know that the rear window defogger is activated.

The rear window defogger will turn off about 10 minutes after the button is pressed. If you need additional warming time, press the button again.

This button activates the heated mirrors.

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.