2009 GMC Sierra 1500 Crew Cab Owner's Manual - Page 209

Climate Control System (With Air Conditioning) With this system the heating, cooling, and ventilation can be controlled. 9 (Fan Control): Turn clockwise or counterclockwise to increase or decrease the fan speed. Turn the knob all the way counterclockwise to turn the front system off. Air Delivery Mode Control: Turn clockwise or counterclockwise to change the direction of the airflow inside the vehicle. The knob can be positioned between two modes to select a combination of those modes. Select from the following: H (Vent): Air is directed to the instrument panel outlets. ) (Bi-Level): Air is divided between the instrument panel and floor outlets. 6 (Floor): A. Fan Control B. Temperature Control C. Air Delivery Mode Control D. Air Conditioning E. Outside Air F. Recirculation G. Rear Window Defogger Air is directed to the floor outlets, with some air directed to the windshield and side window outlets. In this mode, the system automatically selects outside air. Recirculation cannot be selected in floor mode. - (Defog): This mode clears the windows of fog or moisture. Air is directed to the windshield, floor outlets, and side window vents. 0 (Defrost): This mode removes fog or frost from the windshield more quickly. Air is directed to the windshield and the side window vents, with some air directed to the floor vents. The system automatically forces outside air into the vehicle. 3-25 Temperature Control: Turn clockwise or counterclockwise to increase or decrease the temperature inside the vehicle.