GMC 2003 Sonoma Owner's Manual page 147

Cooling
On hot days, open the windows to let hot inside air
escape; then close them. This helps to reduce the time
it takes for your vehicle to cool down. It also helps
the system to operate more efficiently.
A/C (Air Conditioning): Turn the knob to the A/C
position to turn the air-conditioning system on or
off. When the system is on, this setting cools and
dehumidifies the air entering your vehicle and directs it
through the floor outlets as well as the instrument
panel outlets.
MAX A/C (Maximum Air Conditioning): This mode
recirculates much of the air inside your vehicle so
it cools quickly. It directs most of the air through the
instrument panel outlets and a small amount through the
floor outlets.
-
(Blend): Use this mode to direct half the air to the
windshield and half to the floor outlets. Close the
center outlets to help defrost the side windows more
quickly. In this mode, the system will automatically force
outside air into your vehicle and it will also run the
air-conditioning compressor, unless it falls below the
temperature at which air conditioning is effective.
You may notice a slight change in engine performance
when the air-conditioning compressor shuts off and
turns on again. This is normal. The system is designed
to make adjustments to help with fuel economy while
still maintaining the selected temperature.
For quick cool down on hot days, do the following:
1. Select A/C.
2. Select the coolest temperature.
3. Select the highest fan speed.
On cool, but sunny days, the sun may warm the upper
part of your body, but the lower part may not be
warm enough. To remedy this, do the following:
1. Select the bi-level mode.
2. Select the temperature.
3. Select the fan speed.
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.
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