2002 GMC Envoy Owner's Manual - Page 181

(Recirculation): Press this button to limit the amount of outside air entering your vehicle. 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. If you select recirculation while in defrost, defog or floor, the light on the button will flash and go out to let you know this is not allowed. This is 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. Be sure A/C OFF is not selected to allow the air conditioning compressor to run automatically and help dehumidify the air. (Air Conditioning): Press this button to turn the air conditioning compressor on and off. 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, the A/C OFF text will flash to let you know this is not allowed. This is to prevent fogging. FRONT (Defrost): Press this button to defrost the windshield. The system will automatically control the fan speed if you select defrost from AUTO. 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. Air Conditioning 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. If your vehicle has the manual system, for quick cool-down on very hot days, use the airflow from the panel outlets, press recirculation and air conditioning with the temperature control in the blue area. If this max air conditioning setting is used for long periods of time, the air in your vehicle may become too cold and dry. For normal cooling on hot days, use air conditioning without recirculation with the temperature control in the blue area. 3-7