1996 GMC Safari Owner's Manual - Page 129

Air Conditioning Before using your vehicle's air conditioning,open the windows to clear the vehicle of hot air. This reducesthe 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 LO may enhance the front A/C performance by allowing trapped refrigerant in the rear lines to circulate. The rear air conditioningsystem 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. Thisis normal because the system is designed to cycle the compressor on and off to keep the desired temperature. Heating On cold days, use HEATER with the temperature knob in the red area. Outside air will be brought in through the floor outlets.The heater works best if you keep your windows closed while using it. If you use the optional enginecoolant 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. . 3-5