2001 GMC Sierra 1500 Pickup Owner's Manual - Page 199

Air Conditioning On hot days, open the windows long enough to let hot air inside escape. This reduces the time it takes for your vehicle to cool down. Then keep your windows closed for the air conditioner to work its best. The RECIRCULATION button allows the air inside your vehicle to be recirculated. This setting helps to maximize your air conditioner's performance and your vehicle's fuel economy. This setting also cools air the fastest and can be used to keep unwanted odors and/or dust from entering the vehicle. When using the air conditioner, turn off the RECIRCULATION button after the vehicle reaches a comfortable interior temperature. When the right knob on the control panel is between HEATER and DEFROST, the recirculation feature will not function to reduce window fogging. The A/C button, below the mode knob, allows the air coming into your vehicle to be cooled. This setting is useful for normal cooling on hot days. When you use A/C with the RECIRCULATION button pushed in, turn off recirculation as soon as the vehicle reaches a comfortable interior temperature. Maximum air conditioning performance is obtained by pressing the A/C button, the RECIRCULATION button and turning the temperature knob fully counterclockwise to the blue area. This setting also cools air the fastest. After the vehicle's interior reaches a comfortable temperature, press the OUTSIDE AIR button to place the air conditioning system in the normal mode. Passenger Compartment Air Filter (If Equipped) If your vehicle has air conditioning, it is equipped with a passenger compartment air filter, which filters outside air entering the vehicle. For information on replacing the filter see "Passenger Compartment Air Filter" in the Index. 3-12