clutch CHEVROLET EXPRESS 1999 Owners Manual

5-20
Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the fan is spinning slower and the clutch is
not fully engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading, trailer
towing and/or high outside temperatures, the fan
speed increases as the clutch more fully engages. So
you may hear an increase in fan noise. This is normal
and should not be mistaken as the transmission slipping
or making extra shifts. It is merely the cooling system
functioning properly. The fan will slow down when
additional cooling is not required and the clutch
partially disengages.
You may also hear this fan noise when you start
the engine. It will go away as the fan clutch
partially disengages.
If a Tire Goes Flat
It's unusual for a tire to ªblow outº while you're driving,
especially if you maintain your tires properly. If air goes
out of a tire, it's much more likely to leak out slowly.
But if you should ever have a ªblowout,º here are a few
tips about what to expect and what to do:
If a front tire fails, the flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off
the accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like
a skid and may require the same correction you'd use
in a skid. In any rear blowout, remove your foot from
the accelerator pedal. Get the vehicle under control by
steering the way you want the vehicle to go. It may be
very bumpy and noisy, but you can still steer. Gently
brake to a stop
-- well off the road if possible.
If a tire goes flat, the next part shows how to use your
jacking equipment to change a flat tire safely.

6-12
Engine:

Removal or rendering engine speed governor
(if equipped) inoperative so as to allow engine
speed to exceed manufacturer specifications.
Fan and Drive:

Removal of fan clutch (if equipped) or rendering
clutch inoperative.

Removal of the fan shroud (if equipped).
Air Intake:

Removal of the air cleaner silencer.

Modification of the air cleaner.
Exhaust:

Removal of the muffler and/or resonator.

Removal of the exhaust pipes and exhaust
pipe clamps.Engine Oil (Gasoline Engine)
If your vehicle has a diesel engine, see ªEngine Oil
(Diesel Engine)º in the Diesel Engine Supplement.
Checking Engine Oil
It's a good idea to check your engine oil every time you
get fuel. In order to get an accurate reading, the oil must
be warm and the vehicle must be on level ground.
The engine oil dipstick
has a yellow handle and is
located near the center of
the engine compartment.
See ªEngine Compartment
Overviewº in the Index
for more information
on location.
Turn off the engine and give the oil several minutes to
drain back into the oil pan. If you don't, the oil dipstick
might not show the actual level.

6-67
NAME CIRCUITS PROTECTED
ETC Electronic Throttle Control
RR BLOWER Rear Auxiliary Blower
Motor Relays
CNG Compressed Natural Gas
ENG
-I Heated O2 Sensors, Mass Air
Flow Sensor, Evap Canister Purge
Valve, Crankshaft Position Sensor,
Secondary Air Injection Relay
(Diesel), Water in Fuel Sensor
(Diesel), Fuel Heater (Diesel),
Glowplug Relay (Diesel),
Wastegate Solenoid (Diesel)
ECM
-I Ignition Coil, Camshaft Position
Sensor, VCM, Fuel Injectors,
Coil Driver
IGN
-E Air Conditioning Clutch Relay
SPARE Spare Fuse
SPARE Spare Fuse
SPARE Spare FuseNAME CIRCUITS PROTECTED
A/C Air Conditioning Clutch Relay
HORN Horn Relay, Underhood Lamp(s)
ECM
-B Fuel Pump Relay, VCM, PCM,
Fuel Pump and Engine Oil
Pressure Switch
SPARE Spare Fuse
SPARE Spare Fuse
AUX A Upfitter Provisions
AUX B Upfitter Provisions
A/C RELAY Air Conditioning
HORN RELAY Horn
A.I.R. RELAY Air
FUEL
PUMP RELAYFuel Pump
STARTER
RELAYStarter
ABS EXPORT
RELAYABS Export