1999 BUICK CENTURY coolant temperature

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2-20 To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord. The
cord is attached to the underside of the vehicle's
diagonal brace, which is located above the air
cleaner assembly.
3. Plug it into a normal, grounded 110
-volt AC outlet.
CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the wrong
kind of extension cord could overheat and cause
a fire. You could be seriously injured. Plug the
cord into a properly grounded three
-prong
11 0
-volt AC outlet. If the cord won't reach, use a
heavy
-duty three-prong extension cord rated for
at least 15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts. If you don't, it could
be damaged.How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead of
trying to list everything here, we ask that you contact
your dealer in the area where you'll be parking your
vehicle. The dealer can give you the best advice for that
particular area.
Automatic Transaxle Operation
Your automatic transaxle will have a shift lever on the
steering column.
The graphic shown above is displayed on your
instrument panel cluster in reference to your steering
column shift lever.

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2-55 Low Traction Light
If you have the Enhanced
Traction System, this light
will also come on when
the system is limiting
wheel spin.
You may feel or hear the system working, but this is
normal. Slippery road conditions may exist if the low
traction light comes on, so adjust your driving
accordingly. The light will stay on for a few seconds
after the Enhanced Traction System stops limiting wheel
spin. See ªEnhanced Traction Systemº in the Index.
The low traction light also comes on briefly when you
turn the ignition key to RUN. If the light doesn't come
on then, have it fixed so it will be there to tell you when
the Enhanced Traction System is active.
Engine Coolant Temperature Light
This light tells you that your
engine coolant has
overheated or your radiator
cooling fan is not working.
The light should come on briefly when your ignition is
turned on to show you that it is working.
If you have been operating your vehicle under normal
driving conditions, you should pull off the road, stop
your vehicle and turn off the engine as soon as possible.
The ªProblems on the Roadº section of this
manual shows what to do. See ªEngine Overheatingº
in the Index.

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2-56 Engine Coolant Temperature Gage
You have a gage that shows
the engine coolant
temperature. If the gage
pointer moves into the red
area, your engine is too hot!
That reading means the same thing as the warning light.
It means that your engine coolant has overheated. If you
have been operating your vehicle under normal driving
conditions, you should pull off the road, stop your
vehicle and turn off the engine as soon as possible.
The ªProblems on the Roadº section of this
manual shows what to do. See ªEngine Overheatingº
in the Index.
Low Coolant Warning Light
If the LOW COOLANT
light comes on, your system
is low on coolant and the
engine may overheat. See
ªEngine Coolantº in the
Index and have your vehicle
serviced as soon as you can.
The light will come on briefly when your ignition is
turned on to show you that it is working properly.

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3-4
Heating
On cold days, use HTR with the temperature knob all
the way in the red area. The system will bring in outside
air, heat it and send it to the floor ducts.
If your vehicle has an engine coolant heater, you can use
it to help your system provide warm air faster when it's
cold outside
-- 0
F (-18
C) or lower. An engine coolant
heater warms the coolant your engine and heating
system use to provide heat. See ªEngine Coolant
Heaterº in the Index.
Ventilation
For mild outside temperatures when little heating or
cooling is needed, use VENT to direct outside air
through your vehicle. Your vehicle also has the
flow
-through ventilation system described later in
this section.
Defogging and Defrosting
Your system has two settings for clearing the front and
side windows. To defrost the windows quickly, use
FRONT with the temperature knob all the way in the red
area. To warm passengers while keeping the windows
clear, use BLEND.
Dual ComforTemp Climate Control
(If Equipped)
With this system, the driver and passenger can maintain
separate temperatures. The system works best if you
keep your windows closed while using it.
Fan Control
The left knob labeled FAN controls the fan
speed selection.
If the airflow seems very low when the fan is adjusted to
the highest setting regardless of the mode setting, your
passenger compartment air filter may need to be
replaced. See ªMaintenance Scheduleº or ªPassenger
Compartment Air Filterº in the Index.

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3-6
FRONT: This setting directs most of the air
through the defroster and side window vents. Some of
the air goes to the floor ducts and the side window vents.
The air conditioning compressor will run automatically
in this setting unless the outside temperature is below
40
F (4
C). (Even when the compressor is running, you
can control the temperature.)
Air Conditioning
On very hot days, open the windows long enough to let
hot, inside air escape. This reduces the time for the
vehicle to cool down.
For a quick cool
-down on very hot days, use MAX with
the temperature knob and lever all the way in the blue
area. If this setting is used for long periods of time, the
air in your vehicle may become too dry.
For normal cooling on hot days, use NORM with the
temperature knob and lever in the blue area. The system
will bring in outside air and cool it.
On cool, but sunny days, the sun may warm your upper
body, but your lower body may not be warm enough.
You can use BI
-LEV and set the temperature knob to a
comfortable setting. The system will bring in outside air
and direct it to your upper body, while sending slightly
warmed air to your lower body. You may notice this
temperature difference more at some times than others.Heating
On cold days, use HTR with the temperature knob and
lever all the way in the red area. The system will bring
in outside air, heat it and send it to the floor ducts.
If your vehicle has an engine coolant heater, you can use
it to help your system provide warm air faster when it's
cold outside
-- 0
F (-18
C) or lower. An engine
coolant heater warms the coolant your engine and
heating system use to provide heat. See ªEngine Coolant
Heaterº in the Index.
Ventilation
For mild outside temperatures, when little heating or
cooling is needed, use VENT to direct outside air through
your vehicle. Your vehicle also has the flow
-through
ventilation system described later in this section.
Defogging and Defrosting
Your system has two settings for clearing the front and side
windows. To defrost the windows quickly, use FRONT with
the temperature knob all the way in the red area.
For maximum defroster performance, set both driver and
passenger temperature controls to the warmest setting.
To warm passengers while keeping the windows clear,
use BLEND.

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3-9
RECIRC: This setting recirculates much of the air
inside your vehicle. This setting is not permitted in
FRONT defrost mode and is only permitted in
WINDSHIELD/FLOOR mode if the compressor is
turned on. The indicator light will be lit when
recirculation is engaged, but will light for one second
and then turn off if selected when not permitted.
Heating (Engine Coolant Heater)
If your vehicle has an engine coolant heater, you can use
it to help your system provide warm air faster when it's
cold outside
-- 0
F (-18
C) or lower. An engine
coolant heater warms the coolant your engine and
heating system use to provide heat. See ªEngine Coolant
Heaterº in the Index.
Defogging and Defrosting
Your system has two settings for clearing the front and
side windows. To defrost the windows quickly, press the
FRONT button; set the temperature to 90
F (32
C),
select high fan speed and turn the DUAL button off. To
warm passengers while keeping the windows clear, push
the AIR FLOW button until WINDSHIELD/FLOOR
appears in the display. Select fan speed for comfort and
windshield clearing performance.
Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog from the rear window. Press the button to
turn the rear defogger on. It will turn itself off after
about 10 minutes. If you turn it on again, the rear
defogger will only run for about five minutes before
turning off. You can also turn it off by pressing the
button again. The picture above on the left refers to the
defogger button that is found on a Manual Single Zone
Climate Control system or Dual ComforTemp Climate
Control system; the button on the right is found on the
Dual Automatic ComforTemp Climate Control system.

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5-9
Engine Overheating
You will find a coolant temperature gage and a hot
engine warning light on your instrument panel. See
ªEngine Coolant Temperature Gageº and ªEngine
Coolant Temperature Warning Lightº in the Index. You
also have a LOW COOLANT warning light on your
instrument panel. See ªLow Coolant Warning Lightº in
the Index.
Overheated Engine Protection
Operating Mode
This emergency operating mode allows your vehicle to
be driven to a safe place in an emergency situation.
Should an overheated engine condition exist, an
overheat protection mode which alternates firing groups
of three cylinders helps prevent engine damage. In this
mode, you will notice a significant loss in power and
engine performance. The low coolant light may come on
and the temperature gage will indicate an overheat
condition exists. Towing a trailer in the overheat
protection mode should be avoided.
NOTICE:
After driving in the overheated engine protection
operating mode, to avoid engine damage, allow
the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair
the cause of coolant loss and change the oil.
See ªEngine Oilº in the Index.

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6-21
Radiator Pressure Cap
NOTICE:
Your radiator cap is a 15 psi (105 kPa)
pressure
-type cap and must be tightly installed to
prevent coolant loss and possible engine damage
from overheating. Be sure the arrows on the cap
line up with the overflow tube on the radiator
filler neck.
When you replace your radiator pressure cap, an
ACDelco
cap is recommended.
Thermostat
Engine coolant temperature is controlled by a thermostat
in the engine coolant system. The thermostat stops the
flow of coolant through the radiator until the coolant
reaches a preset temperature.
When you replace your thermostat, an ACDelco


thermostat is recommended.
Engine Coolant
The cooling system in your vehicle is filled with
DEX
-COOL
engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX
-COOL
extended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem with
engine overheating or if you need to add coolant to your
radiator, see ªEngine Overheatingº in the Index.
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 lights and gages work as
they should.