length GMC ENVOY 1999 Owners Manual

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Mode Knob - Automatic Operation
The right knob on the control panel allows you to
choose the direction of air delivery. When the system is
set for automatic operation, sensors will control the air
delivery mode. Air will come primarily from the floor or
instrument panel outlets, with some air directed to the
windshield to prevent fogging.
When the system is in AUTO mode, the air conditioning
light will turn on, and the recirculation and outside air
lights turn off. With the system in full auto control (both
the fan and mode knobs in AUTO), you still have the
ability to override any function. However, continually
overriding the outside air or the A/C compressor will limit
the ability of the system to cool the vehicle quickly.
If you push a button for a function which is not
available, the light next to that button will flash three
times to alert you that it's not available.
To find your comfort zone, start with the 74
F (23
C)
setting and allow about 20 minutes for the system to
adjust the temperature if necessary.
With the automatic setting, the air conditioning compressor
automatically cycles when needed to cool the air. In cold
weather, when the system senses the need for heat, the
airflow will be directed out the floor outlets. As the
interior temperature approaches the desired setting, theblower speed will decrease. To maintain interior comfort,
the airflow will adjust between the instrument panel air
outlets and floor outlets. On bright sunny days in cool
weather, the airflow may come out of the air conditioning
and floor outlets (bi
-level mode) to maintain comfort and
prevent stuffiness.
To avoid blowing cold air in cold weather, the system will
delay turning on the fan until warm air is available. The
length of delay depends on the outside air temperature,
engine coolant temperature or the time since the engine
was last started. As the coolant warms up, the blower fan
speed will gradually increase and air will flow from the
heater outlets, with some airflow to the windshield to
prevent fogging under most normal conditions.
If your vehicle is sitting out on a warm day and you
have the fan set on AUTO, the air will first flow out of
the floor air outlets for a few seconds. That is normal.
This is to expel hot air from the air outlets. As the air is
cooled, the airflow will move through the air
conditioning outlets.
Be careful not to put anything over the solar sensor
located around the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.
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Drunken Driving
Death and injury associated with drinking and driving is
a national tragedy. It's the number one contributor to
the highway death toll, claiming thousands of victims
every year.
Alcohol affects four things that anyone needs to drive
a vehicle:

Judgment

Muscular Coordination

Vision

Attentiveness.
Police records show that almost half of all motor
vehicle
-related deaths involve alcohol. In most cases,
these deaths are the result of someone who was drinking
and driving. In recent years, over 17,000 annual motor
vehicle
-related deaths have been associated with the use
of alcohol, with more than 300,000 people injured.
Many adults
-- by some estimates, nearly half the adult
population
-- choose never to drink alcohol, so they
never drive after drinking. For persons under 21, it's
against the law in every U.S. state to drink alcohol.
There are good medical, psychological and
developmental reasons for these laws.The obvious way to solve the leading highway safety
problem is for people never to drink alcohol and then
drive. But what if people do? How much is ªtoo muchº
if the driver plans to drive? It's a lot less than many
might think. Although it depends on each person and
situation, here is some general information on
the problem.
The Blood Alcohol Concentration (BAC) of someone
who is drinking depends upon four things:

The amount of alcohol consumed

The drinker's body weight

The amount of food that is consumed before and
during drinking

The length of time it has taken the drinker to
consume the alcohol.
According to the American Medical Association, a
180
-lb. (82 kg) person who drinks three 12-ounce
(355 ml) bottles of beer in an hour will end up with a
BAC of about 0.06 percent. The person would reach the
same BAC by drinking three 4
-ounce (120 ml) glasses
of wine or three mixed drinks if each had 1
-1/2 ounces
(45 ml) of a liquor like whiskey, gin or vodka.
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When driving downhill, avoid turns that take you
across the incline of the hill. A hill that's not too
steep to drive down may be too steep to drive across.
You could roll over if you don't drive straight down.

Never go downhill with the transmission in
NEUTRAL (N). This is called ªfree
-wheeling.º Your
brakes will have to do all the work and could
overheat and fade.
Q:Am I likely to stall when going downhill?
A:It's much more likely to happen going uphill. But if
it happens going downhill, here's what to do.

Stop your vehicle by applying the regular brakes.
Apply the parking brake.

Shift to PARK (P) and, while still braking, restart
the engine.

Shift back to a low gear, release the parking brake,
and drive straight down.

If the engine won't start, get out and get help.
Driving Across an Incline
Sooner or later, an off-road trail will probably go across
the incline of a hill. If this happens, you have to decidewhether to try to drive across the incline. Here are some
things to consider:

A hill that can be driven straight up or down may be
too steep to drive across. When you go straight up or
down a hill, the length of the wheel base (the distance
from the front wheels to the rear wheels) reduces the
likelihood the vehicle will tumble end over end. But
when you drive across an incline, the much more
narrow track width (the distance between the left and
right wheels) may not prevent the vehicle from tilting
and rolling over. Also, driving across an incline puts
more weight on the downhill wheels. This could cause
a downhill slide or a rollover.

Surface conditions can be a problem when you drive
across a hill. Loose gravel, muddy spots, or even wet
grass can cause your tires to slip sideways, downhill.
If the vehicle slips sideways, it can hit something
that will trip it (a rock, a rut, etc.) and roll over.

Hidden obstacles can make the steepness of the
incline even worse. If you drive across a rock with
the uphill wheels, or if the downhill wheels drop into
a rut or depression, your vehicle can tilt even more.
For reasons like these, you need to decide carefully
whether to try to drive across an incline. Just because the
trail goes across the incline doesn't mean you have to
drive it. The last vehicle to try it might have rolled over.
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Air Conditioning Refrigerants
Not all air conditioning refrigerants are the same.
If the air conditioning system in your vehicle needs
refrigerant, be sure the proper refrigerant is used.
If you're not sure, ask your dealer.
Normal Maintenance
Replacement Parts
Replacement part numbers listed in this section are
based on the latest information available at the time of
printing, and are subject to change. If a part listed in this
manual is not the same as the part used in your vehicle
when it was built, or if you have any questions, please
contact your GMC dealer.
Thermostat 12559051. . . . . . . . . . . . . . . . . . . . . . . . .
Oil Filter PF52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Cleaner Filter A1163C. . . . . . . . . . . . . . . . . . . . . .
PCV Valve CV769C. . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic Transmission Filter Kit 24200796. . . . . .
Spark Plugs 41
-932 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Filter GF481. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Windshield
Wiper Blade Trico (20 inches/50.8 cm). . . . . . . . . .
Backglass Wiper Blade Trico (14 inches/35.6 cm). . .
Vehicle Dimensions
Wheelbase 107.0 inches (271.8 cm). . . . . . . . . . . . . .
Length 181.5 inches (460.0 cm). . . . . . . . . . . . . . . . .
Height 67.0 inches (170.2 cm). . . . . . . . . . . . . . . . . . .
Width 67.8 inches (172.2 cm). . . . . . . . . . . . . . . . . . .
Front Tread 57.3 inches (145.4 cm). . . . . . . . . . . . . . .
Rear Tread 55.1 inches (139.9 cm). . . . . . . . . . . . . . .
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