1998 GMC ENVOY cooling

Resynchronization Resynchronization may be necessary due to the security
method used by this system. The transmitter does not
send the
same signal twice to the receiver. The receiver
will
not respond to a signal it has been sent previously.
This prevents anyone
from recording and playing back
the signal from the transmitter.
To resynchronize your transmitter, stand close to your
vehicle and press and hold the LOCK and UNLOCK
buttons on the transmitter at the same time for seven
seconds. The door locks should cycle to confirm
synchronization.
If the locks do not cycle. see your
dealer for service.
LiftgateLiftglass
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 windows are shut.
Turn the fan on your heating or cooling
system to its highest speed with the setting
on any airflow selection except
RECIRCULATION. That will force outside
air into your vehicle. See “Comfort
Controls” in the Index.
If you have air outlets on or under the
instrument panel, open them
all the way.
See “Engine Exhaust” in the Index.
2-9
I
ProCarManuals.com

I
Comfort Controls
With this system, you can control the heating, cooling
and ventilation in your vehicle.
AUTO: If the knob is in AUTO, the fan speed will vary
as the system maintains
the selected temperature.
Temperature Knob
Electronic Climate Control System
Fan Control
The knob on the left side of the climate control panel
controls the fan speed.
To manually increase airflow,
move the knob to the right. To manually decrease
airflow, move it to the left.
OFF: If the knob is in OFF, outside air will still enter
the vehicle, and will be directed based on the position of
the mode knob. The middle knob
on the control panel lets
you select the
desired air temperature in your vehicle. This knob will
allow you
to adjust the interior air temperature
independently of the function knob setting. Turn the
knob to the right toward 82 for warmer air. Turn the
knob to the left toward
66 for cooler air.
Full Hot: If you turn the temperature knob past 82°F
(2SoC), the system will
go into the “full hot” mode. The
system will remain at that maximum heating setting and
the
fan will blow at the speed the fan knob is set to. If
the fan is in AUTO, it will run at full speed.
Full Cold: If you turn the temperature knob past 66°F
(19” C), the system will go into the “full cold” mode.
The system will remain at that maximum cooling setting
and the fan will blow at the speed the fan knob is set to.
If the fan is in AUTO, it will run at full speed.
Choosing either maximum setting will not cause the
system to heat or cool any faster.
3-2
ProCarManuals.com

Mode Knob - Manual Operation
The right knob on the control panel allows you to
choose the direction
of air delivery.
You can choose to set the climate control system
operations yourself, or let the system work for you by
placing the system
in AUTO mode. See “Mode
Knob
- Automatic Operation” earlier in this section.
/J PANEL: This setting directs most of the air
through the instrument panel outlets and a small amount
through the floor outlets.
’@ BI-LEVEL: Air is delivered through the heater
floor outlets as well as the instrument panel outlets.
+# HEATER: This setting directs most of the
warmed air through the heater floor outlets and some air
through the windshield defroster outlets.
‘/J BLEND: Airflow is divided equally between the
heater floor outlet and the windshield defroster outlets.
The air conditioning compressor may run
to dehumidify
the air to prevent window fogging.
+0
-bo
0
WO
DEFROST This setting directs most air through
the windshield defroster outlets and some through the
heater outlets. The air conditioning compressor may
run
to dehumidify the air to prevent window fogging.
a OUTSIDE AIR: Press this button to force the
system to
use outside air. Press it again to close off the
outside air.
Pressing the
OUTSIDE AIR button will cancel the
RECIRCULATION button.
RECIRCULATION: Press this button to limit
the amount
oi’ fresh air entering your vehicle. This is
helpful when
you are trying to limit odors entering your
vehicle. In the AUTO mode, the system will use
recirculation as necessary to cool
the air. Pressing the
recirculation button will change the operation to
a
manual mode and the air will recirculate non-stop.
RECIRCULATION may be selected
with the fan control
in OFF to limit odors, outside air and dust from entering
your vehicle.
Pressing the RECIRCULATlON button will cancel the
OUTSIDE AIR button.
a A/C: 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.
Air conditioning will be automatically disabled when
the outside temperature drops below a level which air
conditioning is ineffective.
Remember that
in order for the automatic system to perform
well,
it needs A/C to provide cooling performance.
3-4
ProCarManuals.com

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.
Heating
For quick cool-down on very hot days, A/C should be
enabled with the temperature knob turned
to the left and
the OUTSIDE
AIR button should not be active. This
setting should be used to keep odors and/or dust from
entering the vehicle. For normal cooling on hot days,
use
A/C with the temperature knob turned to the left.
On cool but sunny days, use BI-LEVEL
A/C to deliver
warm air to the floor and cooler air to the instrument
panel outlets.
When the air conditioner is on, you may sometimes
notice slight changes
in your vehicle’s engine speed
and power.
This is normal because the system is
designed to cycle the compressor on and off to keep the
desired temperature. The heater
works best
if you keep your windows closed
while using it.
On cold days, use HEATER with the
temperature knob turned
to the right. BLEND is useful
in cool weather when
you have fog or ice on the
windshield
or side windows.
If you use the optional engine coolant heater before
starting your engine, your heating system will produce
warmer air faster to heat the passenger compartment in
cold weather. See “Engine Coolant Heater”
in the Index.
Ventilation System
For mild outside temperatures when little heating or
cooling is needed, use PANEL with the OUTSIDE
AIR
button enabled to direct outside air through your vehicle.
Airflow is through the instrument panel outlets.
Your vehicle’s ventilation system supplies outside air to
the inside
of your vehicle when it is moving. When the
vehicle is not moving, you can get outside air to flow
through by selecting
any mode and any fan speed.
3-5
!
ProCarManuals.com

Driving in Water
Light rain causes no special off-road driving problems.
But heavy rain can mean flash flooding, and
flood
waters demand extreme caution.
Find
out how deep the water is before you drive through
it. If' it's deep enough to cover your wheel hubs. axles or
exhaust pipe, don't try it -- you probably won't get
through.
Also, water that deep can damage your axle
and other vehicle parts.
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.
' 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 "Driving Through Wdter" 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
da1nage. Also, check the fuel lines and cooling
system for any leakage.
4-26
ProCarManuals.com

0
0
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.
‘ A CAUTION:
If you don’t shift down, your I 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. 0
0
/I CAC rION:
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.
0
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.
4-35
I
ProCarManuals.com

Driving with a Trailer
A CAUTION: I
0
0
0
If you have a rear-most window open and you
pull a trailer with your vehicle, carbon monoxide
(CO) could come into your vehicle. You can’t see
or smell
CO. It can cause unconsciousness or
death. (See ‘(Engine Exhaust” in the Index.) To
maximize your safety when towing a trailer:
Have your exhaust system inspected for
leaks, and make necessary repairs before
starting on your trip.
Keep the rear-most windows closed.
If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main
heating or cooling system on and with the
fan on any speed. This will bring fresh,
outside air into your vehicle.
Do not use
RECIRCULATION because it only
recirculates the air inside your vehicle. (See
“Comfort Controls” in the Index.)
Towing a trailer requires a certain amount of experience, ~
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the
trailer. And always keep in mind that the vehicle you
arc
driving is now a good deal longer and not nearly as
responsive as your vehicle is by itself.
Before you
start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, tires and mirror adjustment. If the trailer has
electric brakes, start your vehicle and trailer moving and
then apply the trailer brake controller by hand to be sure
the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to
be sure that the
load is secure, and that the lamps and any trailer brakes
are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as you 1
would when driving your vehicle without a trailer. This
can help you avoid situations that require heavy braking
and sudden turns.
4-48
ProCarManuals.com

When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
0 Start your engine;
Shift into a gear; and
0 Release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling
a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission fluid (don’t
overfill), engine
oil, axle lubricant, belt, cooling system
and brake adjustment. Each of these is covered in this
manual, and the Index will help you find them quickly.
If you’re trailering, it’s
a good idea to review these
sections before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
ProCarManuals.com