1. NOISE
Fan noise is sometimes evident under the following normal conditions:
a. When clutch is engaged for maximum cooling.
b. During first few minutes after start-up until the clutch can re-distribute the silicone fluid back to its normal disengaged operating condition.
2. LOOSENESS
Under various temperature conditions, there is a visible lateral movement that can be observed at the tip of the fan blade. This is a normal condition due to the type of bearing used. Approximately 1/4″ maximum lateral movement measured at the fan tip is allowable. This is not cause for replacement.
3. SILICONE FLUID LEAK
The operation of the unit is generally not affected by small fluid leaks which may occur in the area around the bearing assembly. However, if the degree of leakage appears excessive, proceed to item 4.
4. ENGINE OVERHEATING
a. Start with a cool engine to insure complete fan clutch disengagement.
b. If the fan and clutch assembly free-wheels with no drag (revolves over 5 times when spun by hand), the clutch should be replaced. If clutch performs properly with a slight drag go to Step C.
Testing a fan clutch by holding the small hub with one hand and rotating the aluminum housing in a clockwise/counterclockwise motion will cause the clutch to free-wheel, which is a normal condition when operated in this manner. This should not be considered a test by which replacement is determined.
c. Position thermometer so that it is located between the fan blades and radiator. This can be achieved by inserting the sensor through one of the existing holes in the fan shroud or fan guard, or by placing between the radiator and the shroud. On some models, it may be necessary to drill a 3/16″ hole in the fan shroud to insert thermometer.
d. with thermometer in position, cover radiator grille sufficiently to induce a high engine temperature. Start engine and turn on A/C if equipped, operate at 2,000 rpm.
e. Observe thermometer reading when clutch engages. It will take approximately 5 to 10 minutes for the temperature to become high enough to allow engagement of the fan clutch. This will be indicated by an increase or roar in fan air noise and by a drop in the thermometer reading of approximately 5-15°F (3-9 °C). If the clutch did not engage between 150-195°F (66-91 °C) the unit should be replaced. Be sure fan clutch was disengaged at beginning of test.
If no sharp increase in fan noise or temperature drop was observed and the fan noise level was constantly high from start of test to 190°F (88°C), the unit should be replaced.
f. As soon as the clutch engages, remove the radiator grille cover and turn off the A/C to assist in engine cooling. The engine should be run at approximately 1500 rpm.
g. After several minutes the fan clutch should disengage, as indicated by a reduction in fan speed and roar.
If the fan clutch fails to function as described, it should be replaced.
