1998 GMC Safari Owner's Manual - Page 158

If your vehicle has rear air conditioning, settingon it LOW may enhance the front C performance by N allowing trapped refrigerant the rearlines to circulate. in The rear air conditioning system will only send cooled air if the front system on. It can still be used to is circulate air, even the front system is if off. When the air conditioning, DEFROST or BLEND on, is you may notice a slight increase decrease in engine or speed, due to compressor operation. This normal is because the system is designed to cycle compressor the on and off to keep the desired temperature. Defrosting Use DEFROST to remove fog or from the ice windshield quickly in extremely cold conditions. The temperature knob should be in red area and the the fan control toward high. air conditioning compressor The may operate in this settingto dehumidify the air. The BLEND setting useful for cold weather with a is large numberof passengers or very humid conditions to help keep the windshield clear. Ventilation System For mild outside temperatures when little heating or cooling is needed, use VENT direct outside air to On cold days, use HEATER with the temperature knob through your vehicle. Air will flow through the in the red area. Outside air will be broughtthrough in instrument panel vents. the floor outlets. The heater works best if you keep your Your vehicle's flow-through ventilation system supplies windows closed while using it. outside air to the inside of your vehicle when is it If you use the optional engine coolant heater before moving. Withthe side windows closed, air will flow into starting your engine, your heating system will produce the front air inlet grilles at the base the windshield, of warmer air faster to heat the passenger compartment in through the vehicle and the rear air exhaust valve. out cold weather. See "Engine Coolant Heater" the Index. in ter or Outside air will also en( the vehicle when the heater the air conditioning is running. fan Heating