1999 GMC YUKON heater

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5-10 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
-- AUTOMATIC OVERDRIVE (
).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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5-11
Cooling System
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 Fan
If the coolant inside the coolant recovery tank is boiling,
don't do anything else until it cools down.
The coolant level should be at or above the COLD 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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5-12
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.
NOTICE: (Continued)
NOTICE: (Continued)
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.
How to Add Coolant to the Coolant
Recovery Tank
If you haven't found a problem yet, but the coolant level
isn't at or above the COLD 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.)

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5-13
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.
CAUTION:
You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol
and it will burn if the engine parts are hot
enough. Don't spill coolant on a hot engine.

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6-24
A 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant will:

Give freezing protection down to
-34F (-37C).

Give boiling protection up to 265F (129C).

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning gages work as they should.
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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6-25
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 coolant recovery tank is located on the passenger's
side at the rear corner of the engine compartment.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the COLD
mark, or a little higher. When your engine is warm, the
level should be at the HOT mark, or a little higher.

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9-3
Compact Disc Care 3-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Player 3-14, 3-16 . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Player Errors 3-15, 3-19 . . . . . . . . . . . . . . . . . .
Compass, Electronic 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compass, Rearview Mirror with 2-51 . . . . . . . . . . . . . . . . . . .
Console Storage 2-55, 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Console-Mounted CD Changer 3-16 . . . . . . . . . . . . . . . . . . . .
Control of a Vehicle 4-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convenience Net 2-58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convex Outside Mirror 2-55 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-23, 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater, Engine 2-24 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Recovery Tank 5-12 . . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling System 5-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Courtesy Transportation 8-8 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cruise Control 2-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cupholders 2-56, 2-57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Customer Assistance for Text Telephone Users 8-4 . . . . . . . . .
Customer Assistance Information 8-1 . . . . . . . . . . . . . . . . . . .
Customer Satisfaction Procedure 8-2 . . . . . . . . . . . . . . . . . . . .
Damage, Finish 6-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Damage, Sheet Metal 6-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps 2-47 . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamps Indicator Light 2-81 . . . . . . . . . . . .
Dead Battery 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defects, Reporting Safety 8-10 . . . . . . . . . . . . . . . . . . . . . . . .
Defensive Driving 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogger, Rear Window 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogging 3-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrosting 3-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dolby Noise Reduction 3-11 . . . . . . . . . . . . . . . . . . . . . . . . . .
Dome Lamps 2-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Door
Child Security Locks 2
-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Locks 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Panel 2-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear 2-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Side 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Pocket 2-57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver Position 1-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving
City 4
-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defensive 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Freeway 4-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In a Blizzard 4-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In the Rain 4-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Night 4-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-Road 4-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Curves 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Grades While Towing a Trailer 4-51 . . . . . . . . . . . . . . .
On Hill and Mountain Roads 4-36 . . . . . . . . . . . . . . . . . . . .
On Snow and Ice 4-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Through Water 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wet Roads 4-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Winter 4-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
With a Trailer 4-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken Driving 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric Tailgate Glass Release 2-39 . . . . . . . . . . . . . . . . . . .
Electrical Equipment, Adding 2-23, 3-22, 6-56 . . . . . . . . . . .
Electrical System 6-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview Mirror with
Compass/Temperature Display/Headlamp Delay 2
-51 . . . .
Electrochromic Heated Outside Rearview Mirrors 2-54, 3-7 .

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9-4
Electronic Compass 2-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine 6-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Cleaner/Filter 6-15, 6-64 . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-23, 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater 2-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Level Check 7-35 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Temperature Gage 2-76 . . . . . . . . . . . . . . . . . . . . .
Cooling System 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust 2-36, 4-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-37 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your 2-22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Oil 6-11, 6-65, 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding 6-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additives 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking 6-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Gage 2-79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Used 6-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Change 6-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Equipment, Adding to the Outside of Your Vehicle 6-3 . . . . . .
Ethanol 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust, Engine 2-36, 4-41 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exit Lighting and Delayed Illumination 2-49 . . . . . . . . . . . . .
Exterior Lamps 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fabric Cleaning 6-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Feature Customization 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver's Door Alarm Delay 2-19 . . . . . . . . . . . . . . . . . . . . .
Keyless Entry Verification 2-17 . . . . . . . . . . . . . . . . . . . . . .
Leaving Programming Mode 2-19 . . . . . . . . . . . . . . . . . . . .
Lockout Prevention 2-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . Theft
-Deterrent Arming Method 2-18 . . . . . . . . . . . . . . . . .
Theft-Deterrent Arming Verification 2-19 . . . . . . . . . . . . . .
Filling a Portable Fuel Container 6-8 . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter, Air Cleaner 6-15, 6-64 . . . . . . . . . . . . . . . . . . . . . . . . .
Filter, Engine Oil 6-14, 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Care 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Damage 6-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
First Gear, Automatic Transmission 2-27 . . . . . . . . . . . . . . . .
Flashers, Hazard Warning 5-2 . . . . . . . . . . . . . . . . . . . . . . . . .
Flat Tire, Changing 5-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacities 6-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Leak Check 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluids and Lubricants 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fog Lamps 2-48, 6-36, 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . .
Folding the Rear Seat 1-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Foreign Countries, Fuel 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Four-Wheel Drive 2-28, 6-21 . . . . . . . . . . . . . . . . . . . . . . . . .
French Language Manual ii. . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle 6
-22, 7-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Locking Feature 2-28 . . . . . . . . . . . . . . . . . . . . . . .
Front Park/Turn Signal Bulb Replacement 6-36, 6-61 . . . . . .
Front Sidemarker Lamp Bulb Replacement 6-36, 6-61 . . . . . .
Front Towing 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel 6-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Canada 6-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filling a Portable Container 6-8 . . . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gage 2-82 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In Foreign Countries 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Capacity 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuses and Circuit Breakers 6-57 . . . . . . . . . . . . . . . . . . . . . . .