1999 CHEVROLET VENTURE heater

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5-12
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 (D) or
THIRD (3).
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, idle the engine for 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. Also, see ªOverheated
Engine Protection Operating Modeº listed previously in
this section.
You may decide not to lift the hood but to get service
help right away.
Cooling System
When you decide it's safe to lift the hood, here's what
you'll see:
A. Radiator Pressure Cap
B. Electric Engine Cooling Fans
C. Coolant Recovery Tank
CAUTION:
An electric engine cooling fan under the hood can
start up even when the engine is not running and
can injure you. Keep hands, clothing and tools
away from any underhood electric fan.

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5-13
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 FULL
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.
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.
See ªOverheated Engine Protection Operating
Modeº in the Index.

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5-14
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.
If there seems to be no leak, with the engine on, check to
see if the electric engine cooling fans are running. If the
engine is overheating, both fans should be running. If
they aren't, your vehicle needs service.
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 FULL 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.)
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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5-15
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.
When the coolant in the coolant recovery tank is at or
above the FULL COLD mark, start your vehicle.
If the overheat warning continues, there's one more
thing you can try. You can add the proper coolant
mixture directly to the radiator, but be sure the cooling
system is cool before you do it.

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6-22
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.
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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6-23
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 engine coolant reservoir is located on the driver's
side of the vehicle, above the engine air cleaner/filter.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the FULL
COLD mark, or a little higher. When your engine is
warm, the level should be above the FULL COLD mark
or a little higher.

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6-59
Circuit
BreakersUsage
HEADLAMP DRL Control Module, Headlamp and
Instrument Panel Dimmer Switch
PWR WDO Front Power Windows
PWR SEAT/PSD 6
-Way Power Seat(s) and Rear
Side Door Actuator Motor
FRT HVAC/HI
BLWRBlower Motor Hi Speed
Relay ModuleFuses Usage
SWC
BACKLIGHTSteering Wheel Radio Control
Switches (Illumination)
ELEC PRNDL Instrument Cluster to PRNDL
Indicators
PWR MIRROR Power Remote Control
Mirror Switch
CRUISE Cruise Control Module, Switch
and Release Switch
PWR QTR
VENTInterior Lamps and Multifunction
Switch (Power Vent Switch)
FRT
WPR/WSHRWindshield Wiper/Washer Motor
and Switch
PASS KEY PASS
-Key System
PWR LOCK Body Control Module (BCM)
HTD MIRROR Heated Mirrors
RH T/LP Not Used
RR FOG LP Not Used
CIGAR/DLC Cigarette Lighter and Data Link
Connector (DLC)
T/SIG Turn Signal Switch
RR HVAC Rear Blower Motor, Rear
Heater
-A/C Control, Temperature
Door Actuator (Rear)

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6-60
Fuses Usage
SWC ACCY Steering Wheel Radio
Control Switches
HAZARD Turn Signal Switch
RR PWR SCKT Rear Electric Accessory
Plug Housing
DRL Daytime Running Lamps (DRL)
Control Module
LH T/LP Not Used
RR DEFOG Rear Window Defogger Relay,
Heated Mirrors
FRT PWR SCKT Front Electric Accessory Plug
Housing
SIR Inflatable Restraint
Control Module
FRT HVAC
LOW/MED
BLWRHeater
-A/C Control
MALL/RADIO/
DICBCM, Driver Information Display,
Rear Seat Audio, ELC Sensor
and Relay
STOP LAMP Stoplamp SwitchFuses Usage
ABS MOD
BATTElectronic Brake Control
Module/Electronic Brake Traction
Control Module (EBCM/EBTCM)
CAN VENT
SOLEvaporative Emissions (EVAP)
Canister Vent Solonoid Valve
ELC Electronic Level Control (ELC)
Air Compressor and ELC Relay,
Trailer Harness
CTSY LAMP BCM
IGN 1 BCM, Electronic Brake Control
Indicator Lamp Driver Module,
Instrument Panel Cluster, Rear
Side Door Actuator Control
Module, Rear Window
Wiper/Washer and Multifunction
Switch (Fog Lamp
Switch/Traction Control Switch)
and Stoplamp/Torque Converter
Clutch (TCC) Switch
RR WPR WSHR Rear Window Wiper Motor, Rear
Window Wiper/Washer and
Multifunction Switch (Rear
Window Wiper/Washer Switch)