1994 GMC Sonoma Owner's Manual - Page 119

OFF': This setting turns off all heating functions. Some outside air still will come out of the heater outlet whenever the vehicle is moving forward. MAX A/C: Air inside your vehicle is recirculated to maximize your air conditioner's performance and your vehicle's fuel economy. This setting cools the air the fastest and should be used to keep "unwanted odors" from entering vehicle.. NORM A/C: This setting cools outside air and directs it through the instrument panel vents. This setting is useful for normal cooling on hot days. BI-LEV A/C: Outside air is delivered through the heater floor vents and the instrument panel vents. This setting is useful in cool weather with bright sunlight. VENT: Airflow is through the instrument panel vents. Set the upper knob to the temperature desired. Thissetting is useful for mild outside temperatures, when little heating or cooling is desired. HEAT Heated air comes out through the heater floorvents and windshield defroster vents, This setting useful for cold weather. is BLEND: Airflow is divided equallybetween the heater floor vent and the windshield defroster vents. This setting is useful in cool weather when you have fog or iceon the windshield or side windows. DEF: This setting directs most air through the windshield defroster vents and some through the heater vents. This setting is useful when you have fog or ice on the windshield. Engine Coolant Heater (Engine Block Heater) If you use the optional engine coolantheater 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. Audio Systems Your Delco' audio system has been designed to operate easily and give years of listening pleasure. But you will get the most enjoyment out of it if you acquaint yourself with it first. Find out what your Delco@ system can do and how to operate all its controls, to be sure you're gettingthe most out of the advanced engineering that went into it. Be aware that hearing damage from loud noise is almost undetectable until it is toolate. Your hearing can adapt to higher volumes of sound. Sound that seems normal can be loud and harmful to your hearing. Take precautions by adjusting the volume control on your radio to a safe sound level before your hearing adapts to it.