GMC 2007 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.
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