heating GMC YUKON 1999 Owner's Manual

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1-3 Power Lumbar Adjustment
Your vehicle has a power lumbar adjuster. You can
increase or decrease lumbar support in an area of the
lower seatback.
To increase support, press and hold the front of the
rocker switch. Let go of the switch when the lower
seatback reaches the desired level of support.
To decrease support, press and hold the rear of the
rocker switch. Let go of the switch when the lower
seatback reaches the desired level of support.
Heated Front Seats
The control for the driver's side heated seat is located on
the left side of the seat. The control for the right front
passenger is located on the right side of the passenger
seat. Move the switch forward to MED or HIGH
temperature to turn on the heating elements in the seat.
The right front passenger's safety belt must be buckled
before the heating elements in that seat will operate. To
turn the heated seats off, move the switch rearward to
OFF. For information on heated rear seats, see ªHeated
Rear Seatsº in the Index.

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1-8
Heated Rear Seats
The controls for the heated
rear seats are located on the
rear of the center floor
console, below the rear seat
audio controls.Press the top of the switch to HI or the bottom of the
switch to LO to turn on the heating elements in the
outside rear seat positions. The text HI or LO on the
switch will illuminate to indicate that the heated seat
elements are operating. The switch on the left side
operates the left seat and the switch on the right side
operates the right seat. The rear seat outside passenger's
safety belt must be attached before the heating element
in that seat will operate. To turn the heated seats off,
move the switch to the center. For more information on
heated front seats, see ªHeated Front Seatsº in
the Index.

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2-11
Rear Doors
CAUTION:
It can be dangerous to drive with the tailgate
glass, tailgate or rear doors 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 tailgate glass, tailgate
or rear doors open or if electrical wiring or other
cable connections must pass through the seal
between the body and the tailgate glass, tailgate
or rear doors:

Make sure all other windows are shut.

Turn the fan on your heating or cooling
system to its highest speed with the setting on
VENT. 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.
Tailgate Glass and Tailgate
If your vehicle has a tailgate, you must raise the rear
glass before lowering the tailgate.
To open the glass from the outside, use your key. With
the key in the lock, turn the key clockwise to release the
glass, then lift it up.
To release the glass from the inside, use the electric
tailgate glass release switch on the instrument panel. For
more information, see ªTailgate
-- Electric Glass
Releaseº in the Index.
To open the tailgate, lift up on the handle while pulling
the tailgate toward you.
Close the tailgate before closing the rear glass. After
closing the tailgate, make sure the tailgate is securely
latched by pulling it toward you. After closing the rear
glass, pull up on its handle to make sure it is locked.

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2-61
Ashtrays and Cigarette Lighter
Front Ashtray
The front ashtray is located at the bottom of the
instrument panel. Pull on the notch in the ashtray door to
open it.
NOTICE:
If you store paper or other things that burn in
your ashtrays, they could be set on fire by
cigarettes or other smoking materials. That could
cause a fire and possibly damage your vehicle. Do
not store papers and other things that burn in
your ashtrays.
To remove the front ashtray, press the retainer spring
and pivot the ashtray toward you. To replace the ashtray,
place the bottom part of the ashtray on the pivot bar at
the bottom of its mounting on the instrument panel.
Then rotate the ashtray back to its original position.
Rear Door Ashtrays
To use a rear ashtray, flip the lid open.
To remove a rear ashtray, open the lid and pull the
ashtray assembly upward.
To use the cigarette lighter, push it in all the way, and let
go. When it's done heating, it will pop back by itself.
NOTICE:
Holding a cigarette lighter in with your hand
while it is heating can make it overload,
damaging the lighter and the heating element.
Just push the lighter all the way in and let go.
When it's done heating, it will pop back by itself.

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2-76 Engine Coolant Temperature Gage
This gage shows the engine
coolant temperature.
It also provides an indicator of how hard your vehicle is
working. During a majority of the operation, the gage
will read 210
F (100
C) or less. If you are pulling a
load or going up hills, it is normal for the temperature to
fluctuate and approach the 260
F (160
C) mark. If the
gage reaches the 260
F (160
C) mark, it indicates that
the cooling system is working beyond its capacity.
The ªProblems on the Road,º section of this manual
shows what to do. See ªEngine Overheatingº in
the Index.
Malfunction Indicator Lamp
(Service Engine Soon Light)
Your vehicle is equipped
with a computer which
monitors operation of the
fuel, ignition and emission
control systems.
This system is called OBD II (On
-Board
Diagnostics
-Second Generation) and is intended to
assure that emissions are at acceptable levels for the life
of the vehicle, helping to produce a cleaner
environment. The SERVICE ENGINE SOON light
comes on to indicate that there is a problem and service
is required. Malfunctions often will be indicated by the
system before any problem is apparent. This may
prevent more serious damage to your vehicle. This
system is also designed to assist your service technician
in correctly diagnosing any malfunction.

3-
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3-1
Section 3 Comfort Controls and Audio Systems
In this section, you'll find out how to operate the comfort control and audio systems offered with your vehicle. Be
sure to read about the particular systems supplied with your vehicle.
3
-2 Comfort Controls
3
-3 Rear Air Conditioning
3
-4 Air Conditioning
3
-5 Heating
3
-5 Ventilation System
3
-6 Defogging and Defrosting
3
-7 Rear Window Defogger
3
-7 Audio Systems
3
-7 Setting the Clock
3
-8AM-FM Stereo with Cassette Tape Player3
-12 CD Adapter Kit
3
-12 Rear Seat Audio (RSA)
3
-14 Remote Compact Disc Player (If Equipped)
3
-16 Console-Mounted CD Changer
3
-19 Theft-Deterrent Feature
3
-21 Understanding Radio Reception
3
-21 Tips About Your Audio System
3
-22 Care of Your Cassette Tape Player
3
-24 Care of Your Compact Discs
3
-24 Fixed Mast Antenna

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3-2
Comfort Controls
Heater and Air Conditioning
Control System
Fan Knob
The knob on the left side of the heating system control
panel controls the fan speed. The knob has four speed
positions. To increase airflow, move the knob toward
HI. To decrease airflow, move it toward LO. To turn the
fan off, move the knob to OFF. If you have the air
conditioner on, moving the fan knob to OFF also turns
off the A/C compressor.
In OFF, while driving, air will flow through the floor
outlets. The mode knob will not redirect the airflow to
other selected outlet positions. This is normal operation
for the OFF position.Temperature Knob
The middle knob on the control panel lets you select the
relative temperature of the air flowing into the passenger
area of your vehicle. This knob will allow you to adjust
the relative air temperature independently of the
function knob setting. 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. The control knob
can be placed in any position between any two mode
settings to blend the flow of air.
VENT: This setting directs air through the
instrument panel outlets.
VENT/HEAT: Use this setting to divide airflow
between the floor outlets and instrument panel outlets.
HEATER: This setting directs air through the
floor outlets.
DEFOG: This setting directs air to the heater
outlets and toward the windshield.

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3-5
With the A/C on, turn the temperature knob to MAX for
maximum cooling. This setting also puts the system in
the recirculation mode and helps to maximize your air
conditioner's performance and your vehicle's fuel
economy. This setting also cools the air the fastest. After
the vehicle's interior reaches a comfortable temperature,
turn the temperature knob clockwise to place the air
conditioning system in the normal mode.
Heating
The heater works best if you keep your windows closed
while using it. On cold days, use the HEATER or
VENT/HEAT setting with the temperature knob in
the red area.
If you use the engine coolant heater before starting your
engine in cold weather, 20
F (
-8
C) or lower, your
heating system will produce warmer air faster, to heat
the passenger compartment in cold weather.
The use of an engine coolant heater also 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. For more information, see ªEngine
Coolant Heaterº in the Index.
Ventilation System
For mild outside temperatures when little heating or
cooling is needed, use VENT to direct outside air
through your vehicle. Air will flow 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 fan is running, unless you have the
recirculation button pushed in. For more information on
the recirculation button, see ªAir Conditioningº earlier
in this section.

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3-6
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, or
close the outlets altogether. When you close an outlet, it
will increase the flow of air coming out of any outlets
that are open. These outlets do not completely shut off
airflow when in a closed vent position.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
blower fan to HI 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 hood air deflectors may adversely
affect the performance of the heating and air
conditioning system.
Defogging and Defrosting
On cool, humid days, use DEFOG to keep the
windshield and side windows clear. Use DEFROST to
remove fog or ice from the windshield in extremely
humid or cold conditions. Use DEFROST with the
temperature knob toward the red area and the fan control
toward HI.

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4-49 Trailer Brakes
If your trailer weighs more than 1,000 lbs. (450 kg)
loaded, then it needs its own brakes
-- and they must be
adequate. Be sure to read and follow the instructions for
the trailer brakes so you'll be able to install, adjust and
maintain them properly.
Your trailer brake system can tap into the vehicle's
hydraulic brake system only if:

The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.

The trailer's brake system will use less than
0.02 cubic inch (0.3 cc) of fluid from your vehicle's
master cylinder. Otherwise, both braking systems
won't work well. You could even lose your brakes.
If everything checks out this far, make the brake tap at
the port on the master cylinder that sends the fluid to the
rear brakes. But don't use copper tubing for this. If
you do, it will bend and finally break off. Use steel
brake tubing.
Driving with a Trailer
CAUTION:
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 ªEngine Exhaustº 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 the
recirculation button or MAX because it
only recirculates the air inside your vehicle.
(See ªComfort Controlsº in the Index.)