2012 GMC Sierra Owner's Manual - Page 268

8-2 Climate Controls 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: 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. The recirculation mode cannot be selected in the defog or defrost mode. When either mode is selected, the system runs the air conditioning compressor, unless the outside temperature is close to freezing. Do not drive the vehicle until all the windows are clear. ? (Recirculation): Press to turn the recirculation mode on. An indicator light comes on to show that recirculation is on. This mode recirculates and helps to quickly cool the air inside the vehicle. It can be used to help prevent outside air and odors from entering the vehicle. The recirculation mode cannot be used with floor, defog or defrost modes. If recirculation is selected with one of these modes, the indicator light flashes three times and then turns off. While in recirculation mode the windows may fog when the weather is cold and damp. To clear the fog, select either the defog or defrost mode and increase the fan speed. The recirculation mode can be turned off by pressing the outside air button, or by turning off the ignition. H (Vent): Air is directed to the instrument panel outlets. ) (Bi-Level): 6 (Floor): Air is divided between the instrument panel and floor outlets. 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. : (Outside Air): This mode clears the windows of fog or moisture. Air is directed to the windshield, floor outlets, and side window vents. - (Defog): Press to turn the outside air mode on. An indicator light comes on to show that outside air is on. In this mode outside air circulates throughout the vehicle. The outside air mode can be used with all modes, but it cannot be used with the recirculation mode.