Fan Clutch: Testing and Inspection

WARNING: Do not operate engine until fan has been first checked for possible cracks and separations.

Run engine at a fast idle speed (1000 RPM) until normal operating temperature is reached. This process can be speeded up by blocking off front of radiator with cardboard. Regardless of temperatures, unit must be operated for at least five minutes immediately before being tested.
Stop engine and, using a glove or a cloth to protect hand, immediately
check effort required to turn fan. If considerable effort is required, it can be assumed that coupling is operating satisfactorily. If very little effort is required to turn fan, it is an indication that coupling is not operating properly and should be replaced.

A coiled bi-metal spring type clutch fan may also be tested while vehicle
is being driven. To check, disconnect bi-metal spring and rotate 90° counterclockwise. This disables temperature-controlled free-wheeling feature and clutch performs like a conventional fan. If this cures overheating condition, replace fan clutch.