1995 GMC Sonoma Owner's Manual - Page 116

The lower knob changes the heater function and determines which outlets the air will flow through (instrument panel, defroster, heater, etc.). OFF - This setting turns off all heating functions. Some outside air will still come outof the heater outlet whenever the vehicle is moving forward. VENT -Airflow is through the instrument panel vents. Set the upper knob to the temperature desired. This setting is useful for mild outside temperatures, when little heating or cooling is desired. BI-LEV - Outside air comesin through the heater floor vents and the instrument panel vents. This setting is useful in cool weather with bright sunlight. HEAT - Heated air comes out through the heater floor vents and windshield defroster vents. This setting is useful for cold weather. BLEND - Airflow is divided equally between the heater floor vent and the windshield defroster vents. This setting is useful in cool weather when you have fog or ice the windshield or sidewindows. on 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 iceon the windshield. Heater/Air Conditioning Controls If your vehicle has air conditioning, your heatedair conditioning controls will look like this. Before using your vehicle's air conditioning,open the windows to clear the vehicle of hot air. The switch with the fan symbol changes the fan speed. To increase the fan speed, push the switch upward toward HI. To decrease the fan speed, push the switch downward toward LO. The upper knob changes the air temperature. Turn the knob clockwise for warmer air. Turn the knob counterclockwise for cooler air. 3-2