1999 GMC SUBURBAN heating

Braking/Anti-lock Brakes
Steering
Driving Tips for Various Road Conditions
Off-Road DrivingRecreational Vehicle Towing
Loading Your Vehicle
Towing a Trailer Heating and Air Conditioning
Setting the Radio ClockRadio/Cassette Player/CD Player
Radio Theft-Deterrent Feature (If Equipped)
Hazard Warning Flashers
Jump Starting
Towing Your VehicleEngine Overheating
Changing a Flat Tire
If You're Stuck
Problems on the Road
Section
5
Section
4
Section
3
Comfort Controls and Audio Systems
Your Driving and the Road
iii

2-10
Liftgate Caution
CAUTION:
It can be dangerous to drive with the liftgate
glass, liftgate 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 liftgate glass, liftgate
or rear doors open or if electrical wiring or other
cable connections must pass through the seal
between the body and the liftgate glass, liftgate
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 MAX A/C. 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.
Liftgate Glass and Liftgate
To open a mechanical lock system from the outside,
insert the key into the lock and turn it counterclockwise
to unlock the glass and liftgate.
The liftgate glass can be opened using the pushbutton on
the liftgate after the doors have been unlocked. This can
be done by using either the power door locks or the
remote keyless entry system.
To open the entire liftgate, lift the handle located in the
center of the door.
To lock a power lock system from the outside, insert the
key into the lock button and turn clockwise. All doors will
lock. You may also use the keyless entry system or the
power door locks to lock the liftgate and liftgate glass.
Panel Doors
To open the rear panel doors, you must open the
passenger's side panel door first. If the door is locked,
insert your door key in the lock and turn it
counterclockwise to unlock it.
To open the passenger's side panel door, pull on the
handle and pull the door open.

2-60
To remove the front ashtray, press the retainer spring
and pull the ashtray toward you. To replace the ashtray,
place the ashtray on the slides at the side of its location
in the instrument panel. Then slide the ashtray back to
its original position.
To use the cigarette lighter, push it in all the way, and let
go. When it's ready, it will pop back out by itself.
NOTICE:
Holding a cigarette lighter in with your hand
while it's 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,
it will pop back by itself.
Accessory Power Outlets
Two accessory power outlets are located near the
cigarette lighter. Use these outlets to power mobile
telephones or other devices designed to operate with
vehicle electrical systems.
The cigarette lighter is designed to fit only in the
receptacle to the right of the accessory power outlets.
Power outlets are also located in the rear cargo area on
the passenger side and in the rear of the center floor
compartment (if equipped with rear seat audio). To use
the outlets, remove the cover by lifting the pull tab.
When not in use, always cover the rear outlet with the
protective cap.

2-74 Engine Coolant Temperature Gage
United States Canada
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 250
F (122
C) mark. If the
gage reaches the 260
F (125
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.
Transmission Temperature Gage (If Equipped)
United States Canada
If your vehicle has a heavy duty automatic transmission,
you will have a transmission temperature gage.
When your ignition is on, the gage shows the temperature
of the transmission fluid. The normal operating range is
from 100
F (38
C) to about 265
F (130
C).
At approximately 265
F (130
C), the message center
will display a TRANS FLUID HOT message and the
transmission will enter a transmission protection mode.
When the transmission enters the protection mode, you
may notice a change in the transmission shifting patterns.
The transmission will return to normal shifting patterns
when the transmission fluid temperature falls below
260
F (127
C).

2-85
The following situations can cause the transmission to
operate at higher temperatures:

Towing a trailer

Hot outside air temperatures

Hauling a heavy load

Low transmission fluid level

High transmission fluid level

Restricted air flow to the radiator and the auxiliary
transmission oil cooler (if equipped).
A temporary solution to hotter transmission operating
temperatures may be to let the transmission cool down.
If the transmission is operated at higher temperatures on
a frequent basis, see ªScheduled Maintenanceº in the
Index for the proper transmission maintenance intervals.LOW COOLANT
This message is displayed
when the cooling system is
low on coolant.
The engine may overheat. See ªEngine Coolantº in the
Index and have your vehicle serviced as soon as you can.
CHECK COOLANT TEMP
This message is displayed
when the cooling system
temperature gets hot.
Check the coolant temperature gage and the coolant
level. See ªEngine Coolantº and ªEngine Coolant
Temperature Gageº in the Index. See ªEngine
Overheatingº in the Index for further information.

2-86 ENGINE OVERHEATED
This message is displayed
when the cooling system
temperature gets too hot.
This message will be displayed after the air conditioning
system has automatically turned off for the engine
coolant protection mode. See ªEngine Overheatingº
in the Index for further information.
REDUCED ENGINE POWER
This message is displayed
when the cooling system
temperature gets too hot
and the engine further
enters the engine coolant
protection mode.
See ªEngine Overheatingº in the Index for
further information.
CHECK ENG OIL PRESSURE
This message is displayed
when the engine oil pressure
is low.
See ªOil Pressure Gageº in the Index for more information.
CHECK ENG OIL LEVEL
This message is displayed
when the engine oil level
is low.
Once oil is added, it may need time to drain and settle in
the engine before this message will turn off. It is best to
let the engine cool down (if it is hot) or warm up (if it is
cold) and cycle the ignition to be sure this message turns
off. Refer to the dipstick for the correct level.
See ªEngine Oilº in the Index on how to check the oil
level and for what type of oil to add.

3-
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 Heater and Air Conditioning Comfort
Controls (If Equipped)
3
-5 Electronic Climate Control System
(If Equipped)
3
-11 Air Conditioning
3
-12 Heating
3
-12 Defogging and Defrosting
3
-12 Rear Window Defogger (If Equipped)
3
-13 Ventilation System
3
-15 Audio Systems
3
-15 Setting the Clock for Systems with
SET Button
3
-15 Setting the Clock for Systems with HR
and MN Buttons
3
-15 AM-FM Stereo3
-17 AM-FM Stereo with Cassette Tape Player
(If Equipped)
3
-19 AM-FM Stereo with Cassette Tape Player
and Automatic Tone Control (If Equipped)
3
-24 AM-FM Stereo with Compact Disc Player
and Automatic Tone Control (If Equipped)
3
-28 Rear Seat Audio (If Equipped)
3
-29 Remote Compact Disc Player (If Equipped)
3
-31 Theft-Deterrent Feature (If Equipped)
3
-34 Understanding Radio Reception
3
-34 Tips About Your Audio System
3
-35 Care of Your Cassette Tape Player
3
-37 Care of Your Compact Discs
3
-37 Care of Your Compact Disc Player
3
-37 Fixed Mast Antenna

3-5 Electronic Climate Control System
(If Equipped)
Fan Control
The knob on the left side of the electronic climate
control panel controls the fan speed. To manually
increase airflow, move the knob clockwise. To manually
decrease airflow, move it counterclockwise.
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.
AUTO: If the knob is in AUTO, the fan speed will vary
as the system maintains the selected temperature.When both the Fan Control and Mode Knobs are in
the AUTO position, the system will then automatically
maintain the desired cabin temperature as selected by
Temperature Knob. Manual control of functions is
also available.
Temperature 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
independent of the function knob setting. Move the
knob clockwise toward 82 for warmer air. Move the
knob counterclockwise toward 66 for cooler air. When
the system is set for automatic operation, sensors will
control the fan/blower speed.
Full Hot: If you turn the temperature knob past
82
F (28
C), the system will go into the ªfull hotº
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 ªfull coldº
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.