2002 GMC YUKON XL DENALI air condition

3-4
(Recirculation): Press this button to limit
the amount of outside air entering the vehicle to a very
small amount. This setting helps limit odors entering the
vehicle and will assist in reaching a comfortable
temperature in very hot temperature conditions.
Pressing recirculation will cause the system to
recirculate interior air continuously and may cause the
vehicle windows to fog if the passenger compartment
floor is excessively wet.
A/C (Air Conditioning): Press this button to turn
the air conditioning on and off. The system will cool and
dehumidify the air inside the vehicle when the A/C light
is on. When in AUTO, the A/C is automatically engaged
when necessary.
Air conditioning will be automatically disabled when
the outside temperature drops below a level at which
air conditioning is effective.Pressing the recirculation button will cancel outside air
operation. To return to normal system operation and to
prevent stale passenger compartment air, be sure to
return to the outside air position.
To help reduce window fogging, recirculation will not
be available in floor, blend or defrost modes. If the
recirculation button is pressed in these modes, the LED
indicator for recirculation will flash three times
indicating that forced outside air is activated and
recirculation is not available.
If the air conditioning system is activated and system
demand is high in situations such as city traffic, idling,
or very hot weather, the system will automatically
switch from outside air to recirculation. The LED
indicator will not change. After demand on the system is
reduced, the system will return back to outside air.

3-5
Mode Knob - Automatic Operation
When the system is set in AUTO mode, sensors will
control the air delivery mode. Air will come primarily
from the floor or instrument panel outlets, with some air
directed to the windshield to prevent fogging.
When the system is in AUTO mode, the air conditioning
light will turn on, and the recirculation and outside air
lights will turn off. With the system in full automatic
control (both the fan and mode knobs in AUTO), you
still have the ability to override any function. However,
continually overriding the outside air or the A/C
compressor will limit the ability of the system to cool
the vehicle quickly.
If you push a button for a function which is not
available, the light next to that button will flash three
times to alert you that it's not available.
To find your comfort zone, start with the 74
F (23
C)
setting and allow about 20 minutes for the system to
adjust the temperature if necessary.With the automatic setting, the air conditioning
compressor automatically cycles when needed to cool
the air. In cold weather, when the system senses the
need for heat, the airflow will be directed out the floor
outlets. As the interior temperature approaches a desired
setting, the fan speed will decrease. To maintain interior
comfort, the airflow will adjust between the instrument
panel outlets and floor outlets. On bright sunny days
in cool weather, the airflow may come out of the
instrument panel and the floor outlets (bi
-level mode)
to maintain comfort and prevent stuffiness.
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 outside air
temperature, engine coolant temperature or the time
since the engine was last started. As the coolant
warms up, the fan speed will gradually increase and
air will flow from the floor outlets, with some airflow
to the windshield to prevent fogging under most
normal conditions.
Be careful not to put anything over the solar sensor
located near the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.

3-6 Rear Air Conditioning and Rear Heater
(With Sunroof)
Your vehicle has the rear air conditioning and rear
heater system combination. Controls are provided to
regulate the temperature, the air delivery location and
the fan speed.
Front ControlTo adjust the fan speed, turn the fan knob located on the
left side to the desired setting.
To select the direction of airflow turn the right knob
located on the control panel to the desired setting.
Generally, the upper vents are used for air conditioning
and the floor vents for heating. The knob can be set to
any blend setting.
To adjust the air temperature, turn the temperature knob
on the center of the control panel to the desired setting.
For warmer air, turn the knob clockwise toward red. For
cooler air, turn the knob counterclockwise toward blue.

3-7 Rear Air Conditioning and Heating Systems
with Electronic Climate Control System
(Without Sunroof)
Front Control
Rear ControlWith this system the rear passengers can control the
temperature of the air flow for the rear seating area.
The climate control panels have three knobs.
To adjust the fan speed, turn the fan knob located on
the left side of the control panel to the desired setting.
The system also has a front AUTO setting that can
automatically change the temperature of the rear seating
area based on information received from the front
control panel. The OFF setting, located on the front
climate control panel, also allows the driver to turn off
the rear passenger seat controls from the front seat.
To adjust the air temperature, turn the temperature knob
located on the center of the control panel clockwise
toward 82
F (28
C) for warmer air and
counterclockwise toward 66
F (19
C) for cooler air.
To direct the airflow, turn the right knob located on
the control panel clockwise or counterclockwise to the
desired mode. Generally, the upper vents are used for air
conditioning and the floor vents for heating. The control
knob can be set to any blend setting.
For rear control operation, use the above instructions.

3-8 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 A/C button, located below the mode knob, allows
the air coming into your vehicle to be cooled. This
setting is useful for normal cooling on hot days.
Use A/C with recirculation on to allow the air inside
your vehicle to be recirculated. This setting will help to
maximize your air conditioner's performance and your
vehicle's fuel economy. This setting also cools the 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
setting and use the outside air setting after the vehicle
reaches a comfortable interior temperature. When the
right knob on the control panel is between floor and
defrost, the recirculation feature will not function.
This helps reduce window fogging.Passenger Compartment Air Filter
Your vehicle is equipped with a passenger compartment
air filter which filters outside air entering the vehicle.
For information on replacing the filter see ªPassenger
Compartment Air Filterº in the Index.
Heating
The heater works best if you keep your windows closed
while using it. On cold days, use the floor or bi
-level
(mode knob set between vent and floor) setting with the
temperature knob in the red area.
On cold days, approximately 32
F (
-0
C) or lower,
you may experience differences in how the transmission
shifts until the engine is warm. This feature
automatically reduces the time it takes for the engine to
reach normal operating temperature and shortens the
time it takes the heater to reach full output.
If you use the engine coolant heater before starting your
engine in cold weather, 20
F (
-8
C) or lower, the
heating system will produce warmer air faster to heat the
passenger compartment.
The use of an engine coolant heater also reduces the
time it takes for the engine to reach normal operating
temperature. For more information, see ªEngine Coolant
Heaterº in the Index.

3-9 Defogging and Defrosting
On cool, humid days, use defog to keep the windshield
and side windows clear. Use defrost to remove fog or ice
from the windshield in extremely humid or cold
conditions. Use defrost with the temperature knob
toward the red area and the fan knob turned all the
way clockwise.
Rear Window Defogger
The lines running across the rear window are the
defogger grid. The lines warm the glass.
To turn on the rear
window defogger, press this
button located below the
mode knob.The rear window defogger will only work if the ignition
is in RUN. For best results, clear the window of as much
snow or ice as possible first.
The defogger will shut itself off after several minutes.
If you need additional warming time, press the button
again. You can turn the defogger off at any time by
pressing the button.
Your vehicle is equipped with heated outside mirrors.
The rear window defogger button will also activate the
heated outside mirrors.
Do not attach a temporary vehicle license, tape or decals
across the defogger grid on the rear window.
NOTICE:
Don't use a razor blade or something else sharp
on the inside of the rear window. If you do, you
could cut or damage the warming grid, and the
repairs wouldn't be covered by your warranty.

3-10 Ventilation System
Your vehicle has air outlets
in the center and on the
sides of the instrument
panel. There are also two
outlets located on the back
of the center console for the
rear seat passengers.
You can move the outlets from side
-to-side and the
louvers up and down to direct the flow of air. The
driver's and passenger's side outlets can be closed. The
two outlets, located on the rear of the center console, can
also be closed. Turn the thumbwheel to the left to shut
off air flow or to the right to allow air flow. When you
close an outlet, it will increase the flow of air coming
out of any outlets that are open. The center outlet,
located on the instrument panel, does not completely
shut off airflow.For mild outside temperatures when little heating or
cooling is needed, use outside air to direct outside air
through your vehicle. Air will flow through the
instrument panel outlets.
Your vehicle's ventilation system supplies outside air
to the inside of your vehicle when it is moving. With
the side windows closed, air will flow into the front air
inlet grilles, through the vehicle, and out the air
exhaust valves.
Outside air will also enter the vehicle when the heater or
the air conditioning fan is running, unless you have the
recirculation button pushed in. For more information on
the recirculation button, see ªAir Conditioningº earlier
in this section.

3-11
Ventilation Tips

Keep the hood and front air inlet free of ice, snow or
any other obstruction (such as leaves). The heater
and defroster will work far better, reducing the
chance of fogging the inside of your windows.

When you enter a vehicle in cold weather, turn the
fan knob all the way to the right for a few moments
before driving. This helps clear the intake ducts of
snow and moisture, and reduces the chance of
fogging the inside of your windows.

Keep the air path under the front seats clear of
objects. This helps air to circulate throughout
your vehicle.

The use of non
-GM approved hood air deflectors
may adversely affect the performance of the heating
and air conditioning system.
Audio Systems
Your audio system has been designed to operate easily
and give years of listening pleasure. You will get the
most enjoyment out of it if you acquaint yourself with it
first. Find out what your audio system can do and how
to operate all of its controls to be sure you're getting the
most out of the advanced engineering that went into it.
Your vehicle has a feature called Retained Accessory
Power (RAP). With RAP, you can play your audio
system even after the ignition is turned off. See
ªRetained Accessory Powerº in the Index.
Setting the Clock
Press and hold HR until the correct hour appears on the
display. Press and hold MN until the correct minute
appears on the display. To display the clock with the
ignition off, press RECALL or HR/MN and the time
will be displayed for a few seconds. There is an initial
two
-second delay before the clock goes into the
time
-set mode.