2004 GMC Sierra 1500 Pickup Owner's Manual - Page 187

Turn the right knob clockwise or counterclockwise to direct the airflow inside of your vehicle. To change the current mode, select one of the following: H (Vent): panel vents. This mode directs air to the instrument )(Bi-Level): on the button will light up, flash three times and turn off when recirculation is selected in these modes.The air-conditioning compressor will also come on when this mode is activated. While in recirculation mode the windows may fog when the weather is cold and damp. To clear the fog, select either the blend or defrost mode and increase fan speed. Temperature Control Driver's Side: The lever on the left side of the climate control panel is used to raise or lower the temperature on the driver's side of the vehicle. This lever also adjusts the temperature to the center console outlets (if equipped). Passenger's Side: The lever on the right side of the climate control panel is used to raise or lower the temperature on the passenger's side of the vehicle. This mode directs half of the air to the instrument panel vents; then directs most of the remaining air to the floor vents. A little air is directed toward the windshield and the side window vents. Cooler air is directed to the upper vents and warmer air to the floor vents. 6 (Floor): This mode directs most of the air to the floor vents with a little air directed to the windshield and the side window vents. h (Recirculation): The recirculation mode is used to recirculate the air inside of your vehicle. Use this mode to help prevent outside odors and/or dust from entering your vehicle or to help cool the air inside of your vehicle more quickly. Press this button to turn the recirculation mode on or off. The light on the recirculation button will illuminate. Recirculation cannot be used in floor, blend or defrost modes. An indicator #(Air Conditioning): Press this button to turn the air-conditioning system on or off. When the button is pressed, an indicator light will come on and the system will begin to cool and dehumidify the air inside of your vehicle. You may notice a slight change in engine performance when the air conditioning compressor shuts off and turns on again. This is normal. 3-23