2002 GMC ENVOY cooling

2-13
To replace the battery in the remote keyless
entry transmitter:
1. Insert a thin coin in the slot between the covers
of the transmitter housing. Gently pry the
transmitter apart.
2. Remove and replace the battery with a three
-volt
CR2032 or equivalent battery, positive (+)
side down.
3. Align the covers and snap them together.
4. Check the operation of the transmitter.
Liftgate/Liftglass
CAUTION:
It can be dangerous to drive with the liftgate or
liftglass open because carbon monoxide (CO) gas
can come into your vehicle. You can't see or smell
CO. It can cause unconsciousness and even death.
If you must drive with the liftgate or liftglass
open or if electrical wiring or other cable
connections must pass through the seal between
the body and the liftgate or liftglass:

Make sure all other windows are shut.

Turn the fan on your heating or cooling
system to its highest speed with the setting
on panel or bi
-level with recirculation off.
That will force outside air into your vehicle.
See ªComfort Controlsº in the Index.

If you have air outlets on or under the
instrument panel, open them all the way.
See ªEngine Exhaustº in the Index.

2-102
DIC Warnings and Messages
Warning messages are displayed on the DIC to notify
the driver that the status of the vehicle has changed and
that some action may be needed by the driver to correct
the condition. More than one message may appear at
one time, they will appear one behind the other. Some
messages may not require immediate action but you
should press the select button to acknowledge that you
received the message and clear it from the display.
Some messages cannot be cleared from the display
because they are more urgent. These message required
action before they can be removed from the DIC display.
The following are the possible messages that can be
displayed and some information about them.
ENGINE COOLANT HOT/IDLE ENGINE
If the cooling system temperature gets hot this message
will appear in the DIC and you will hear a chime. Stop
the vehicle and let the engine idle in PARK (P) to allow
the coolant to reach a safe temperature. This message
will clear when the coolant temperature drops to a safe
operating temperature.ENGINE OVERHEATED/STOP ENGINE
(If Equipped)
If the engine cooling system reaches unsafe
temperatures for operation, this message will appear
in the DIC and you will hear a chime. Stop and turn off
the vehicle as soon as it is safe to do so to avoid severe
damage. This message will clear when the engine has
cooled to a safe operating temperature.
OIL PRESSURE LOW/STOP ENGINE
If low oil pressure levels occur this message will be
displayed on the DIC. Stop the vehicle as soon as safely
possible and do not operate it until the cause of the low
oil pressure has been corrected. Check your oil as soon
as possible and have your vehicle serviced.
BATTERY NOT CHARGING
If the battery is not charging during operation this
message will appear on the DIC. Driving with this
problem could drain your battery. Have the electrical
system checked as soon as possible. Pressing the select
button will acknowledge this message and clear it from
the DIC display.

3-2
Comfort Controls
This section tells you how to use the comfort controls.
With these systems, you can control the heating,
cooling and ventilation in your vehicle. Your vehicle
also has a flow
-through ventilation system described
later in this section.
Comfort Controls Personalization
(If Equipped)
If your vehicle is equipped with the automatic comfort
control system and memory seats and mirrors, you
can store and recall the climate control settings for
temperature, air delivery mode and fan speed for
two different drivers. The personal choice settings
recalled are determined by the transmitter used to enter
the vehicle. After the button with the unlock symbol on
a remote keyless entry transmitter is pressed, the climate
control will adjust to the last settings of the identified
driver. The settings can also be changed by pressing
one of the memory buttons (1 or 2) located on the
driver's door. When adjustments are made, the new
settings are automatically saved for that driver.
Manual Dual Zone Comfort Controls
With this system, you can select different comfort
control settings for the driver and passengers.
Fan Knob
The knob on the left side of the climate control panel
regulates the fan speed. You can choose from
five different fan speeds or turn the fan off.
Driver's Side Temperature Lever
The lever on the left side of the climate control panel is
used to adjust the air temperature on the driver's side,
independent of the temperature set by the passenger.
Slide the lever upward to raise the temperature. Slide the
lever downward to lower the temperature.

3-6
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 clockwise or counterclockwise 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
and fan speed. If you choose the temperature setting of
90
F (32
C), the system will remain at the maximum
heat setting and fan speed. Choosing either maximum
setting will not cause the system 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.
The EXT (exterior) temperature sensor is located in the
front of the vehicle behind the grille. The displayed
temperature is most accurate after the vehicle has been
moving for a few minutes. If the vehicle is stopped and
then restarted within 2 1/2 hours, the sensor will be hot
from the engine heat. In this case, the temperature first
displayed will continue to be the temperature that was
displayed before the vehicle was turned off. The display
will update after the vehicle has been moving for a few
minutes and the sensor has a chance to cool down to the
actual temperature.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. Pushing the fan switch will override this
delay and change the fan to a selected speed.
Manual Operation
You may manually adjust the air delivery mode or fan
speed. Use the mode button to cycle through the
following four air delivery modes:
(Panel): This setting will deliver air to the
instrument panel outlets.
(Bi-Level): This setting will deliver warmer air to
the floor and cooler air to the instrument panel outlets.
(Floor): This setting will deliver air to the
floor outlets.
(Defog): This setting will deliver air to the floor
and windshield outlets.
OFF: Press this button to turn the system off. Some
fresh air will continue to flow through the vehicle from
the floor outlets. The system will try to maintain the
previously chosen temperature setting.

3-7
(Recirculation): Press this button to limit the
amount of outside air entering your vehicle. This is
helpful when you are trying to limit odors entering your
vehicle and for maximum air conditioning performance
in hot weather. Press this button again to allow outside
air to enter the vehicle.
If you select recirculation while in defrost, defog or
floor, the light on the button will flash and go out to let
you know this is not allowed. This is to prevent fogging.
When the weather is cool or damp, operating the system
in recirculation for extended periods of time may cause
fogging of the vehicle's windows. To clear the fog,
select either defog or FRONT defrost. Be sure A/C OFF
is not selected to allow the air conditioning compressor
to run automatically and help dehumidify the air.
(Air Conditioning): Press this button to turn the
air conditioning compressor on and off. When air
conditioning is selected or in AUTO mode, the system
will run the air conditioning automatically to cool and
dehumidify the air entering the vehicle. If you select
A/C OFF while in FRONT defrost, the A/C OFF text
will flash to let you know this is not allowed. This is to
prevent fogging.
FRONT (Defrost): Press this button to defrost the
windshield. The system will automatically control the
fan speed if you select defrost from AUTO. If the
outside temperature is 40
F (4
C) or warmer, your air
conditioning compressor will automatically run to help
dehumidify the air and dry the windshield.
Air Conditioning
On hot days, open the windows long enough to let hot
inside air 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.
If your vehicle has the manual system, for quick
cool
-down on very hot days, use the airflow from the
panel outlets, press recirculation and air conditioning
with the temperature control in the blue area. If this max
air conditioning setting is used for long periods of time,
the air in your vehicle may become too cold and dry.
For normal cooling on hot days, use air conditioning
without recirculation with the temperature control in the
blue area.

3-11 Ventilation System
For mild outside temperatures when little heating
or cooling is needed, use the panel outlet setting
(on the standard system) to direct outside air through
your vehicle. Air will flow through the instrument
panel outlets.
Your vehicle's flow
-through ventilation system supplies
outside air into the vehicle when it's moving. When the
vehicle is not moving, you can get outside air to flow
through by selecting any air delivery mode and any
fan speed.
Your vehicle has air outlets that allow you to adjust
the direction and amount of airflow inside the vehicle.
Move the outlet up or down and move the control in
the center of each outlet side
-to-side to direct the air
from the outlet. Use the thumbwheel under the outlet
to turn the outlet off. For the most efficient airflow
and temperature control, keep the outlet in the fully
opened position.
The rear seat outlets can be used to adjust the airflow
toward either seating area, the floor or upward. Move
the control in the center of each outlet in any direction
to direct airflow.

4-29
If the water isn't too deep, then drive through it slowly.
At fast speeds, water splashes on your ignition system
and your vehicle can stall. Stalling can also occur if you
get your tailpipe under water. And, as long as your
tailpipe is under water, you'll never be able to start your
engine. When you go through water, remember that
when your brakes get wet, it may take you longer
to stop.
CAUTION:
Driving through rushing water can be dangerous.
Deep water can sweep your vehicle downstream
and you and your passengers could drown. If it's
only shallow water, it can still wash away the
ground from under your tires, and you could lose
traction and roll the vehicle over. Don't drive
through rushing water.
See ªDriving Through Waterº in the Index for more
information on driving through water.
After Off-Road Driving
Remove any brush or debris that has collected on the
underbody, chassis or under the hood. These
accumulations can be a fire hazard.
After operation in mud or sand, have the brake linings
cleaned and checked. These substances can cause
glazing and uneven braking. Check the body structure,
steering, suspension, wheels, tires and exhaust system
for damage. Also, check the fuel lines and cooling
system for any leakage.
Your vehicle will require more frequent service due to
off
-road use. Refer to the Maintenance Schedule for
additional information.

4-39
If you drive regularly in steep country, or if you're
planning to visit there, here are some tips that can make
your trips safer and more enjoyable. See ªOff
-Road
Drivingº in the Index for information about
driving off
-road.

Keep your vehicle in good shape. Check all fluid
levels and also the brakes, tires, cooling system and
transmission. These parts can work hard on
mountain roads.

Know how to go down hills. The most important
thing to know is this: let your engine do some of the
slowing down. Shift to a lower gear when you go
down a steep or long hill.
CAUTION:
If you don't shift down, your brakes could get so
hot that they wouldn't work well. You would then
have poor braking or even none going down a hill.
You could crash. Shift down to let your engine
assist your brakes on a steep downhill slope.
CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have to
do all the work of slowing down. They could get so
hot that they wouldn't work well. You would then
have poor braking or even none going down a hill.
You could crash. Always have your engine running
and your vehicle in gear when you go downhill.

Know how to go uphill. You may want to shift down to
a lower gear. The lower gears help cool your engine and
transmission, and you can climb the hill better.

Stay in your own lane when driving on two
-lane roads
in hills or mountains. Don't swing wide or cut across
the center of the road. Drive at speeds that let you stay
in your own lane.

As you go over the top of a hill, be alert. There could be
something in your lane, like a stalled car or an accident.

You may see highway signs on mountains that warn of
special problems. Examples are long grades, passing or
no
-passing zones, a falling rocks area or winding roads.
Be alert to these and take appropriate action.