Which statement about normal mechanical fan clutch operation is false?

The statement regarding a fan clutch varying speed according to engine speed is not accurate. A fan clutch primarily operates based on engine temperature, rather than directly on engine speed.

Normal mechanical fan clutches use a thermosensitive element to engage or disengage the fan based on the temperature of the engine coolant or air passing through the radiator. When the engine temperature rises and reaches a certain threshold, the clutch engages, allowing the fan to spin faster, thereby increasing airflow to cool the engine. Conversely, as the engine cools, the clutch will disengage, allowing the fan to slow down.

While it is true that fan speed can be influenced indirectly by engine speed when the clutch is engaged, the primary control of the fan clutch function is determined by coolant temperature rather than engine speed itself. Understanding this principle is critical in diagnosing overheating issues and ensuring proper engine cooling in vehicles.