Fan Clutch

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Fan Clutch

Electric Fan Clutch

What does a cooling fan clutch do?

A cooling fan clutch is used to electronically engage your engine cooling fan in an on and off cycle to regulate the engine coolant operating temperature. The engagement of the cooling fan is dependant on the need for more or less cooling air to flow through the radiator. The electronic fan clutch is a thermostatically controlled device that when operating in the proper manner, varies the fan speed independently of the engine speed to maintain the optimum coolant temperature of your engine.

When traveling at highway speeds, with moderate outside temperature, the fan should idle along, turning just fast enough to add a little airflow when needed to meet the current cooling requirements. In this manner, the fan noise and drag on the engine are significantly reduced. When reducing speed, the fan clutch will sense higher temperatures through the radiator and engage in increasing fan speed and help maintain constant engine temperature. It may, in fact, cycle as the temperature of the air through the radiator changes, depending on airflow. Because the engine fan clutch engages or disengages when needed, it maximizes fuel efficiency, brings the engine to optimum temperature faster, and typically lasts longer than a non-thermal clutch. The electric fan clutch is a wear item that requires replacement.

If the fan clutch operation is regular when first starting your vehicle, the fan clutch should adequately engage, and the increase in noise and airflow should be noticeable. After about 60 to 90 seconds of engagement, the cooling fan clutch should then disengage, and the sound and airflow will be reduced. The fan will continue to turn but at a much-reduced speed. As the engine warms up and the coolant temperature rises your thermostat opens. The engine coolant will now move under pressure to the radiator to regulate the engine temperature. The fan clutch will sense this and increase the speed of the fan to maintain a normal operating temperature.

Warning Signs of cooling fan clutch trouble or problems:

  • A normal temperature indication at freeway speeds with increasing temperature as the vehicle slows.
  • Engine coolant temperature seems to be stable at speeds but climbs in traffic or while stopped.
  • A rapid increase in the engine coolant temperatures.
  • As the temperature continues to climb the electric fan clutch should start but may not provide enough air to keep the engine from overheating.
  • Excessive fan noise that does not diminish after starting.
  • The engine RPM appears to be higher than normal with higher elevated operating temperatures. This condition means that the fan clutch is frozen and is not releasing. Although this will not result in immediate serious trouble, it will load the engine continually, and fuel economy will be reduced.
  • Your fuel economy has dropped to a noticeable level because the cooling fan is now constantly engaged.

If your vehicle is now encountering any of the symptoms above KLM Performance strongly recommends the cooling fan clutch issue be addressed immediately. The replacement of the failed fan clutch will improve your fuel economy and ensure the lifespan of your engine. 

NOTE: KLM Performance strongly recommends you replace your Radiator Fan Clutch and Water Pump at the same time. These two cooling system parts age at the same rate so if one has failed, the other is probably not far behind. The fan clutch and water pump usually fail in a sequence as one part regulates the operation of the other. To prevent the premature failure of your new cooling fan, it is wise to replace both at the same time.