2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 250

6 (Floor): Air is directed to the floor outlets, with some to the windshield, side window outlets, and second row floor outlets. In this mode, the system automatically selects outside air. - (Defog): This mode clears the windows of fog or moisture. Air is directed to the windshield, floor outlets, and side window vents. In this mode, the system turns off recirculation and runs the air conditioning compressor unless the outside temperature is close to freezing. The recirculation mode cannot be selected while in the defrost mode. If vent, bi-level, or floor mode is selected again, the climate control system displays the previous temperature settings. Do not drive the vehicle until all the windows are clear. # (Air Conditioning): Press to turn the air conditioning (A/C) compressor on and off. An indicator light comes on to show that the air conditioning is on. If this button is pressed when the air conditioning compressor is unavailable due to outside conditions, the indicator flashes three times and then turns off. If the air conditioning is on and the outside temperature drops below a temperature which is too cool for air conditioning to be effective, the air conditioning light turns off to show that the air conditioning mode has been canceled. On hot days, open the windows long enough to let hot inside air escape. This helps to reduce the time it takes for the vehicle to cool down. It also helps the system to operate more efficiently. The air conditioning system removes moisture from the air, so a small amount of water might drip under the vehicle while idling or after turning off the engine. This is normal. 0 (Defrost): This mode removes fog or frost from the windshield more quickly. Air is directed to the windshield and side window vents, with some directed to the floor vents. In this mode, the system automatically forces outside air into the vehicle and runs the air conditioning compressor unless the outside temperature is close to freezing. The recirculation mode cannot be selected while in the defrost mode. The passenger temperature control cannot be activated while in defrost mode. If the PASS button is pressed, the button indicator flashes three times and will not work. If the passenger temperature buttons are adjusted, the driver temperature indicator changes. The passenger temperature will not be displayed. 4-26