Sometimes fan noise is present under the following conditions:
• | The clutch is engaged for maximum cooling. |
• | The noise is present the first 15 seconds to 1 minute after start-up. This condition occurs until the clutch can redistribute the silicone fluid to the normal disengaged operating condition (after settling 2-4 hours). |
Fan noise or an excessive roar generally occurs under all high-speed conditions (2,500 RPM or higher) if the clutch assembly is locked up due to internal failure. If the fan cannot be rotated by hand or there is a rough grating feel as you turn the fan, replace the clutch. Refer to Fan Clutch Replacement .
Inspect a loose fan assembly for wear. Replace a worn assembly as necessary. Under various temperatures, there is a visible lateral movement at the tip of the fan blade. Allow approximately 6.5 mm (1/4 in) maximum lateral movement measured at the fan tip. More movement is cause for replacement.
Small fluid leaks around the bearing assembly will not affect the fan clutch operation. If the leakage appears excessive, replace the fan clutch. Refer to Fan Clutch Replacement .
Inspect for engine overheating as follows:
• | If the clutch does not engage between 65-90°C (150-195°F), the fan clutch should be replaced. Be sure the fan clutch is disengaged at the start of the test. |
• | If the fan noise level is constantly high from the start of the test to 88°C (190°F), without any noticeable noise level increase or drop in temperature, the fan clutch must be replaced. To prevent engine overheating, discontinue the test, past a thermometer reading of 88°C (190°F). |