DESCRIPTION
The thermostatic fan clutch system consists of a silicone-filled coupling which connects fan to pulley. Fan drive is operated by a control valve which is governed by temperature sensitive bimetallic coil or strip. The control valve maintains flow of silicone through drive.
When cooling air temperature is low, fan drive limits fan speed. High air temperature causes bimetallic coil or strip to allow a greater flow of silicone to enter the drive. This increases drag between driven member and driving member, resulting in higher fan speeds and increased cooling.
FAN NOISE
Normal fan noise is sometimes evident when the clutch is engaged for maximum cooling. Fan noise may also be evident during the first few minutes after cold (overnight) start-up. This noise will continue until the clutch can redistribute the silicone fluid back to its normal disengaged operation condition.
Fan clutch replacement is required if fan noise or excessive roar occurs continuously or if fan cannot be rotated by hand. If a roughness is felt as fan is turned by hand, unit must be replaced.
OVERHEATING
If fan and clutch assembly free-wheels with no drag (revolves more than 5 times when spun by hand), replace the clutch.
SILICONE FLUID LEAKS
Fan clutch operation is not affected by small fluid leaks which may occur in the area around the bearing assembly. If excessive leakage appears, replace fan clutch.
