2008 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 204

: (Outside Air): Press this button to turn the outside air mode on. When the button is pressed, an indicator light will come on. When this mode is on, outside air will circulate throughout the vehicle. The outside air mode can be used with all modes, but it cannot be used with the recirculation mode. ?(Recirculation): Press this button to turn the recirculation mode on. When the button is pressed, an indicator light will come on. This mode keeps outside air from entering the vehicle. It can be used to reduce outside air and prevent odors from entering the vehicle. Recirculation may also help cool the air inside the vehicle more quickly once the temperature inside the vehicle is less than the outside temperature. The recirculation mode cannot be used with floor, defog or defrost modes. If recirculation is selected with one of these modes, the indicator light will flash three times and then turn 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. #(Air Conditioning): Press this button to turn the air conditioning system on or off. When this button is pressed, an indicator light on the button will come on to let you know the air conditioning is activated. The air conditioning can be selected in any mode as long as the fan switch is on. The air conditioning system removes moisture from the air, so you may sometimes notice a small amount of water dripping underneath your vehicle while idling or after turning off the engine. This is normal. 3-26