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Your vehicle’s Fan Clutch is a component of the emissions system. Two-way Fan Clutchs are often used with diesel engines while three-way Fan Clutchs are frequently used in passenger vehicles.



What is a Fan Clutch?

The Fan Clutch is a vital part of your vehicle emissions control system. Its job is to reduce toxic air by converting harmful pollutants into less harmful emissions, such as water, carbon dioxide and nitrogen.

How Does a Fan Clutch Work?

A conventional fan clutch is viscously-operated and relies on sensors to detect temperature. A special kind of oil is contained within its reservoir and allowed to flow out of the reservoir through an aperture when the temperature reaches its trigger point. As the oil goes into the function chamber it activates a shaft that causes the fan to rotate. Conversely, when the temperature reduces past the trigger point, the valve allowing the oil to enter will close and the remaining oil in the chamber will discharge through centrifugal force back to the reservoir. As this happens, the rotor will deactivate and the fan will stop. Without this viscous operation, the fan would be directly connected to the driving belt at all times and would provide cooling when not needed. Electrically-operated fan clutches are an alternative and rely on a solenoid controlling a spring-loaded valve.

How Is a Fan Clutch Made?

Fan clutches are produced from high-quality materials meant to withstand vibration and heat. At the front is a bimetallic temperature sensor and beneath the outer cover is a slide valve, chamber, and rotor. The rear side of the case completes the enclosure and mounts to a pulley shaft that is connected to the driving belt.

Why Does a Fan Clutch Fail?

  • The clutch will get stuck in the “on” position.
  • The clutch will fail to engage.

What Are the Symptoms of Failure?

  • Decrease in overall power or fuel efficiency.
  • Excessive noise.
  • Overheating engine.

What Are the Consequences of Failure?

  • Higher costs of operation.
  • Engine damage.

Oil-driven fan clutches are typically found on rear wheel drive vehicles, where the fan itself is forward facing and can draw the air back through the radiator. Electrically-cooled clutch fans are typically used on front wheel drive vehicles, where they are situated to the side.

If you have questions or concerns about fan clutches or any of your vehicle’s components, come into your local pep boys local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.