2007 GMC Acadia Owner's Manual - Page 201

The air conditioning compressor also comes on when this mode is activated unless the outside air temperature is less than 40°F (4°C). 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. # (Air Conditioning): Press this button on the left knob to turn the air conditioning system on or off. When A/C is pressed, an indicator light comes on to show that the air conditioning has been activated. The air conditioning compressor does not operate when outside temperatures fall below 40°F (4°C). The indicator light flashes three times and turns off when outside conditions affect air conditioning operation. This is normal. For quicker cool down on hot days, do the following: 1. Open the windows to let hot air escape. 2. Select the vent mode. 3. Select the air conditioner. 4. Select the coolest temperature. 5. Select the highest fan speed. 6. Close the windows after the hot air has escaped. 7. Once the vehicle's interior temperature is below the outside temperature, select recirculation mode for better cooling. This helps to reduce the time it takes for the vehicle to cool down. It also helps the system to operate more efficiently. Using recirculation for long periods of time may cause the air inside of the vehicle to become too dry. To prevent this from happening, after the inside of the vehicle has cooled, turn the recirculation mode off. The air conditioning system removes moisture from the air, so you might notice a small amount of water dripping underneath the front of center and right rear of the vehicle while idling or after turning off the engine. This is normal. 201