2002 GMC SIERRA Owner's Manual

3-2
Comfort Controls
Heater and Air Conditioning Comfort
Controls
Fan Knob
The knob on the left side of the control panel adjusts the
fan speed. To increase airflow, turn the knob clockwise.
To decrease airflow, turn it counterclockwise. To turn
the fan off, turn the knob to OFF.Temperature Knob
The middle knob on the control panel lets you select the
temperature of the air flowing into the passenger area.
Turn the knob clockwise toward the red area for warmer
air. Turn the knob counterclockwise toward the blue area
for cooler air.
Mode Knob
The right knob on the control panel allows you to
choose the direction of air delivery.
(Vent): This mode directs the air through the
instrument panel outlets and the center floor console
outlets.
(Bi-Level): Air is delivered through the
instrument panel outlets and center floor console outlets,
as well as the floor outlets. The air flow can be divided
between panel and floor depending upon where the knob
is placed. Pressing the A/C button while in this mode
causes cooler air to come out of the instrument panel
outlets and center floor console outlets and warmer air
to come out of the floor outlets.

3-3
(Floor): This mode directs most of the air through
the floor outlets and center floor console outlets, as well
as some air through the windshield defroster outlets and
side window defroster outlets. If air from the center
floor console outlets is not desired, turn the vents off at
the console.
(Defog): Airflow is delivered through the floor
outlets, center floor console outlets, the windshield
defroster outlets and the side window defroster outlets.
The air flow can be divided between floor and defrost
depending upon where the knob is placed. When in
blend mode, the air conditioning compressor may run
to assist in dehumidifying the air and limit window
fogging.
(Defrost): This mode directs most of the air
through the windshield defroster outlets with airflow
also delivered from the side window and the floor
outlets. When in defrost mode, the air conditioning
compressor may run to assist in dehumidifying the air
and limit window fogging.Mode Buttons
(Outside Air): This mode should be used for
normal system operation and directs the system to use
outside air. Using outside air will limit stale air odors
and help to prevent excessively humid interior air
(from wet boots or clothing or maximum passenger
loads) from being redirected onto windows.
Pressing the outside air button will cancel the
recirculation button.
(Recirculation): This mode limits the amount of
outside air entering the vehicle to a very small amount.
This will be helpful to limit odors entering the vehicle
and will assist in reaching comfort 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.
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.

3-4
Recirculation will not be available in floor, blend, or
defrost modes. This helps reduce window fogging.
If the recirculation button is pressed in these modes,
the LED indicator for recirculation will flash three times
indicating that 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 to outside air.
A/C (Air Conditioning): This button is used to
control the air conditioning compressor. Turning the
system on will allow air to be cooled and dehumidified
inside the vehicle.
Air conditioning will be automatically disabled when
the outside air temperature drops below a level at which
air conditioning is effective.
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. When
you use air conditioning with the recirculation button
pressed, turn off recirculation as soon as the vehicle
reaches a comfortable interior temperature.
Using air conditioning with the recirculation mode
active allows the air inside your vehicle to be
recirculated. This setting helps to maximize your air
conditioner's performance and your vehicle's fuel
economy. This setting also cools 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 recirculation and use outside air after the vehicle
reaches a comfortable interior temperature. When the
right knob on the control panel is between floor and
defrost, recirculation will not function to reduce window
fogging.

3-5 Heating
The heater works best if you keep your windows closed
while using it. On cold days, use the floor or bi
-level
modes 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.
Defogging and Defrosting
On cool, humid days, use blend mode to keep the
windshield and side windows clear. Use defrost mode to
remove fog or ice from the windshield in extremely
humid or cold conditions. Use defrost mode with the
temperature knob toward the red area and the fan knob
turned all the way clockwise.

3-6 Rear Window Defogger
The lines running across the rear window are the rear
window defogger. The lines warm the glass.
To turn on the rear window
defogger, press this button
next to the fan 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.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.
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.

3-7 Ventilation System
For mild outside temperatures when little heating or
cooling is needed, use vent and the outside air setting to
direct outside air through your vehicle. Air will flow in
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 compressor is running, unless you
have the recirculation button pressed. For more
information on the recirculation button, see ªAir
Conditioningº earlier in this section.
Your vehicle has air
outlets in the center and
on the sides of your
instrument panel.
You can move the outlets from side
-to-side or up and
down to direct the flow of air. The left driver and
passenger outlets have shut off levers. Turn the lever 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 does not completely shut off airflow.

3-8
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 toward the red area 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.
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.
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 for Systems with HR and
MN Buttons
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.

3-9 AM-FM Stereo with Cassette Tape Player
and Automatic Tone Control
Playing the Radio
PWR (Power): Press this knob to turn the system on
and off.
VOL (Volume): Turn this knob clockwise to increase
volume. Turn it counterclockwise to decrease volume.
The knob is capable of being turned continuously.
RECALL: Pressing this button will display the station
being played or it will display the clock. Clock display
is available with the ignition turned off.SCV (Speed
-Compensated Volume): With SCV, your
audio system adjusts automatically to make up for road
and wind noise as you drive. Set the volume at the
desired level. Turn the control ring behind the upper
knob clockwise to adjust the SCV. Each notch on the
control ring allows for more volume compensation at
faster vehicle speeds. Then, as you drive, SCV
automatically increases the volume, as necessary, to
overcome noise at any speed. The volume level should
always sound the same to you as you drive. If you don't
want to use SCV, turn the control all the way down.
Finding a Station
AM FM: Press this button to switch between AM, FM1
and FM2. The display will show your selection.
TUNE: Press this knob lightly so it extends. Turn it to
choose radio stations. Push the knob back into its stored
position when you're not using it.