1999 GMC ENVOY heater

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4-39
CAUTION:
Snow can trap exhaust gases under your vehicle.
This can cause deadly CO (carbon monoxide) gas
to get inside. CO could overcome you and kill
you. You can't see it or smell it, so you might not
know it is in your vehicle. Clear away snow from
around the base of your vehicle, especially any
that is blocking your exhaust pipe. And check
around again from time to time to be sure snow
doesn't collect there.
Open a window just a little on the side of the
vehicle that's away from the wind. This will help
keep CO out.
Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little faster
than just idle. That is, push the accelerator slightly. This
uses less fuel for the heat that you get and it keeps the
battery charged. You will need a well
-charged battery to
restart the vehicle, and possibly for signaling later on
with your headlamps. Let the heater run for a while.Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine again
and repeat this only when you feel really uncomfortable
from the cold. But do it as little as possible. Preserve the
fuel as long as you can. To help keep warm, you can get
out of the vehicle and do some fairly vigorous exercises
every half hour or so until help comes.
Recreational Vehicle Towing
There may be times when you want to tow your vehicle
behind another vehicle for use at your destination. Be
sure to use the proper towing equipment designed for
recreational vehicle towing. Follow the instructions for
the towing equipment.
When towing your vehicle, turn the ignition to OFF. To
prevent your battery from draining while towing,
remove the RDO BATT fuse from the instrument panel
fuse block. Be sure to replace the fuse when you reach
your destination. See ªFuses and Circuit Breakersº in
the Index.
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5-9 If No Steam Is Coming From Your Engine
If you get an engine overheat warning but see or hear no
steam, the problem may not be too serious. Sometimes
the engine can get a little too hot when you:

Climb a long hill on a hot day.

Stop after high
-speed driving.

Idle for long periods in traffic.

Tow a trailer. See ªDriving on Gradesº in the Index.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. If your air conditioner is on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
3. If you're in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
-- DRIVE (D) or THIRD (3).If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn't come back on, you can
drive normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there's still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you're parked. If you still have the warning, turn off the
engine and get everyone out of the vehicle until it
cools down.
You may decide not to lift the hood but to get service
help right away.
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5-10
When you decide it's safe to lift the hood, here's what
you'll see:
A. Coolant Recovery Tank
B. Radiator Pressure Cap
C. Engine FanIf the coolant inside the coolant recovery tank is boiling,
don't do anything else until it cools down.The coolant level should be at least up to the ADD
mark. If it isn't, you may have a leak in the radiator
hoses, heater hoses, radiator, water pump or somewhere
else in the cooling system.
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5-11
CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don't touch them. If you
do, you can be burned.
Don't run the engine if there is a leak. If you run
the engine, it could lose all coolant. That could
cause an engine fire, and you could be burned.
Get any leak fixed before you drive the vehicle.
NOTICE:
Engine damage from running your engine
without coolant isn't covered by your warranty.
NOTICE:
When adding coolant, it is important that you use
only DEX
-COOL
(silicate-free) coolant.
If coolant other than DEX-COOL is added to the
system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX
-COOL
is not
covered by your new vehicle warranty.
If there seems to be no leak, start the engine again.
See if the engine cooling fan speed increases when idle
speed is doubled by pushing the accelerator pedal
down. If it doesn't, your vehicle needs service. Turn off
the engine.
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5-12 How to Add Coolant to the Coolant
Recovery Tank
If you haven't found a problem yet, but the coolant level
isn't at the ADD mark, add a 50/50 mixture of clean,
drinkable water and DEX
-COOL
engine coolant at the
coolant recovery tank. (See ªEngine Coolantº in the
Index for more information.)
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like alcohol, can boil before the proper
coolant mixture will. Your vehicle's coolant
warning system is set for the proper coolant
mixture. With plain water or the wrong mixture,
your engine could get too hot but you wouldn't
get the overheat warning. Your engine could
catch fire and you or others could be burned. Use
a 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant.
NOTICE:
In cold weather, water can freeze and crack the
engine, radiator, heater core and other parts.
Use the recommended coolant and the proper
coolant mixture.
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6-22
NOTICE:
When adding coolant, it is important that you use
only DEX
-COOL
(silicate-free) coolant.
If coolant other than DEX-COOL is added to the
system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX
-COOL
is not
covered by your new vehicle warranty.
What to Use
Use a mixture of one-half clean, drinkable water and
one
-half DEX-COOL
coolant which won't damage
aluminum parts. If you use this coolant mixture, you
don't need to add anything else.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like alcohol, can boil before the proper
coolant mixture will. Your vehicle's coolant
warning system is set for the proper coolant
mixture. With plain water or the wrong mixture,
your engine could get too hot but you wouldn't
get the overheat warning. Your engine could
catch fire and you or others could be burned. Use
a 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant.
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yellowblue
6-23
NOTICE:
If you use an improper coolant mixture, your
engine could overheat and be badly damaged.
The repair cost wouldn't be covered by your
warranty. Too much water in the mixture can
freeze and crack the engine, radiator, heater core
and other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
NOTICE:
If you use the proper coolant, you don't have to
add extra inhibitors or additives which claim to
improve the system. These can be harmful.
Checking Coolant
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at ADD, or a
little higher. When your engine is warm, the level should
be up to FULL HOT, or a little higher.
Adding Coolant
If you need more coolant, add the proper DEX
-COOL

coolant mixture at the coolant recovery tank.
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9-3
Compact Disc Care 3-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Console Mounted CD Changer 3-18 . . . . . . . . . . . . . . . . . . . .
Content Theft-Deterrent 2-11 . . . . . . . . . . . . . . . . . . . . . . . . .
Control of a Vehicle 4-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convenience Net 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convex Outside Mirror 2-45 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 5-12, 6-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater, Engine 2-17 . . . . . . . . . . . . . . . . . . . . . . . . . .
Courtesy Transportation 8-8 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cruise Control 2-37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Customer Assistance Information 8-1 . . . . . . . . . . . . . . . . . . .
Customer Satisfaction Procedure 8-2 . . . . . . . . . . . . . . . . . . . .
Damage, Finish 6-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Damage, Sheet Metal 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps 2-41 . . . . . . . . . . . . . . . . . . . . . . . . .
Dead Battery 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defects, Reporting Safety 8-10 . . . . . . . . . . . . . . . . . . . . . . . .
Defensive Driving 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogging 3-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrosting 3-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dimensions, Vehicle 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disabilities, GM Mobility Program for Persons with 8-5 . . . .
Dome Lamps 2-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Door Locks 2-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive 2-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive Axle Service 7-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver Information System 2-47 . . . . . . . . . . . . . . . . . . . . . . .
Driver Position 1-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving
City 4
-31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defensive 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Foreign Countries 6
-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Freeway 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Guidelines 4-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hill and Mountain Roads 4-34 . . . . . . . . . . . . . . . . . . . . . . .
In a Blizzard 4-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Night 4-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-Road 4-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Curves 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rainy Conditions 4-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Snowy and Icy Conditions 4-36 . . . . . . . . . . . . . . . . . . . . . .
Through Deep Standing Water 4-30 . . . . . . . . . . . . . . . . . . .
Wet Roads 4-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Winter 4-36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
With a Trailer 4-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving On Grades While Towing a Trailer 4-52 . . . . . . . . . . .
Driving Through Water 4-30 . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken Driving 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Equipment, Adding 3-25, 6-55 . . . . . . . . . . . . . . .
Electrical System 6-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Inside Day/Night Rearview Mirror 2-44 . . . .
Electronic Level Control 4-43 . . . . . . . . . . . . . . . . . . . . . . . . .
Engine 6-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater 2-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Level Check 7-39 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Temperature Gage 2-70 . . . . . . . . . . . . . . . . . . . . .
Exhaust 2-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fan Noise 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-30 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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