2002 GMC Safari Owner's Manual - Page 155

Air Conditioning Before using your vehicle's air conditioning, open the windows to clear the vehicle of hot air. This reduces the time it takes for your vehicle to cool down. Then keep your windows closed for the air conditioner to work at its best. You can use MAX A/C with the temperature knob in the blue area when it's really hot outside and you need to cool the inside air quickly. MAX A/C lets in only a little air from the outside. If you first use MAX A/C, you can then use A/C with the temperature knob in the blue area as soon as the vehicle has cooled down, so outside air will be going through your vehicle. If your vehicle has rear air conditioning, setting it on LOW may enhance the front air conditioning performance by allowing trapped refrigerant in the rear lines to circulate. The rear air conditioning system will only send cooled air if the front system is on. It can still be used to circulate air, even if the front system is off. When the air conditioning, defrost or blend is on, you may notice a slight increase or decrease in engine speed, due to compressor operation. This is normal because the system is designed to cycle the compressor on and off to maintain the desired temperature. Heating On cold days, use the floor setting with the temperature knob in the red area. Outside air will be brought in through the floor ducts. The heater works best if you keep your windows closed while using it. If you use the optional engine coolant heater before starting your engine, your heating system will produce warmer air faster to heat the passenger compartment in cold weather. See "Engine Coolant Heater" in the Index. Defrosting Use defrost to remove fog or ice from the windshield quickly in extremely cold conditions. The temperature knob should be in the red area and the fan control toward high. The air conditioning compressor may operate in this setting to dehumidify the air. The blend setting is useful for cold weather with a large number of passengers or very humid conditions to help keep the windshield clear. 3-6