1999 GMC Sonoma Owner's Manual - Page 126

yellowblue Comfort Controls With these systems, you can control the heating, cooling and ventilation in your vehicle. Mode Knob The right knob on the control panel allows you to choose the direction of air delivery. OFF: This setting turns the system off. Some outside air will still enter the vehicle whenever the vehicle is moving forward. VENT: This setting directs most of the air through the instrument panel outlets and a small amount through the floor outlets. BI-LEVEL: Air is delivered through the heater floor outlets as well as the instrument panel outlets. HEATER: This setting directs most of the warmed air through the heater floor outlets and some air through the windshield defroster outlets. BLEND: Airflow is divided equally between the heater floor outlet and the windshield defroster outlets. DEFROST: This setting directs most air through the windshield defroster outlets and some through the heater outlets. Standard Climate Control System Fan Control The knob on the left side of the heating system control panel controls the fan speed. To increase airflow, turn the knob clockwise. To decrease airflow, turn it counterclockwise. Temperature Knob The middle knob on the control panel lets you select the relative temperature of the air flowing into the passenger area of your vehicle. Turn the knob clockwise toward the red area for warmer air. Turn the knob counterclockwise toward the blue area for cooler air. 3-2