GMC YUKON XL 2003 Manual page 177

Automatic Operation
AUTO (Automatic): When automatic operation is
active the system will control the inside temperature, the
air delivery, and the fan speed.
Use the steps below to place the entire system in
automatic mode:
1. Press the AUTO button.
When AUTO is selected, the display will change to
show the current driver's set temperature,
delivery mode and fan speed. Press the AUTO
button again within five seconds to display
the passenger's set temperature.
If the driver and passenger's temperature settings
are not the same, the opposite side temperature
setting will be displayed for an additional five
seconds. To make the passenger's temperature the
same as the driver's press and hold the AUTO
button for approximately four seconds.
When auto is selected, the air conditioning
operation and air inlet will be automatically
controlled. The air conditioning compressor will run
when the outside temperature is over approximately
40°F (4°C). The air inlet will normally be set to
outside air. If it's hot outside, the air inlet may
automatically switch to recirculate inside air to help
quickly cool down your vehicle. The light on the
button will illuminate in recirculation.
3.
Set the driver's and passenger's temperature.
To find your comfort setting, start with a 74°F
(23°C) temperature setting and allow about
20 minutes for the system to regulate. Turn the
driver's or passenger's side temperature knob
to adjust the temperature setting as necessary. If
you choose the temperature setting of 60°F
(15°C) the system will remain at the maximum
cooling setting. If you choose the temperature
setting of 90°F (32°C) the system will remain at the
maximum heat setting. Choosing either maximum
setting will not cause the vehicle to heat or cool any
faster.
Be careful not to cover the sensor located on the
top of the instrument panel near the windshield.
This sensor regulates air temperature based on sun
load, and also turns on your headlamps.
To avoid blowing cold air in cold weather, the
system will delay turning on the fan until warm air
is available. The length of delay depends on
the engine coolant temperature. Pressing the fan
switch will override this delay and change the fan to
a selected speed.
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