Engine Fan Noise - Chevrolet Avalanche 2004 Owner's Manual

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
5. Then replace the pressure cap. Be sure the
clutch disengages.
pressure cap is hand-tight and fully seated.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
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