How Does Fan Clutch Work? new for 2022

Fans can create a lot of noise and heat, which can affect how a car engine operates. The fan clutch is a device that helps to smooth out the engine’s power delivery by engaging and disengaging the fan belt as needed.

This post will answer your question about “how does fan clutch work?” and provide relevant information.

how does fan clutch work
how does fan clutch work


What is a Fan Clutch?

What is a Fan Clutch?
What is a Fan Clutch?

A fan clutch is a device that connects the water pump shaft and the fan to control which one operates at different speeds. By allowing the fan to operate at lower speeds when it’s not needed, this helps the engine run more efficiently.

How does fan clutch work?

How does fan clutch work?
How does fan clutch work?

Most fan clutches use a silicone-based oil to keep the fan disengaged.

To engage the fan, a fluid is forced through internal valves and into the working area of the clutch. This creates friction between the drive plate and housing, which in turn causes fan to spin.

To disengage the fan, the valves close, which reduces the friction and allows the housing and fan to spin independently of the shaft.

Fan Clutch Varieties

There are three main types of fan: non-thermal, thermal, and electronic. Each uses a silicone fluid to engage and disengage your fan.



Non-thermal clutches work solely based on the speed of the water pump. At low speeds, the clutch allows the fan blade to turn at almost a 1:1 ratio. As speed increases, the silicone fluid within in the clutch loses its ability to transfer energy from the shaft to fan body (and therefore, fan) and fan is then allowed to free-wheel removing its load from engine.

A fan clutch is a type of clutch that uses air flow to help dissipate heat from the engine. A non-thermal clutch, on the other hand, provides a steady flow of cooling air but is always engaged, so it offers lower fuel savings than a thermal-style fan clutch.



The thermal fan clutch operates in response to engine underhood temperatures. When hot air blows across the radiator, it heats a thermal spring mounted at the front of the clutch. This causes valve ports within the clutch to open and allow silicone fluid stored inside a reservoir to pass through these openings.

This engages the fan and drives it. Once the engine is cooled down, the thermal spring rotates back and closes these valve ports, disengaging the fan

The SPT-600, the SPT-800, and the SPT-1000. When buying a thermal fan clutch, consider its speed rating. The Summit Racing website offers different ratings for different types of fans.

Standard-Duty Thermal Fan Clutch

This fan controller adjusts the speed of the fan based on how fast the water pump is spinning. It works best with fans with a lighter pitch.

Heavy-Duty Thermal Fan Clutch

The fan style turns the fan at a speed of 70-90 percent when engaged for increased cooling, and 25-35 percent when disengaged. It is used with deeper-pitch fans (2 1/2 inches of pitch), and works well with high operating rpm.

Severe-Duty Thermal Fan Clutch

Thermal fans used in severe duty environments turn at a much higher speed than those used in less demanding applications. When engaged, they turn the fan at around 80-90% of the shaft speed, while when disengaged they run at a slower 20-30% rate. This type of fan has a larger working surface to help it stay cooler and last longer.



A fan clutch operates similarly to a thermal clutch, but the ECM/PCM signal controls the level of engagement of the EV clutches. Engagement is controlled through ECM/PCM inputs such as coolant temperature, intake manifold temperature, transmission oil temperature, air conditioning pressure and engine oil temperature. These variables are manufacturer-specific and fan speed is dictated based on the cooling requirement.

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A fan clutch is a component that will eventually need to be replaced.

Signs of Worn Fan Clutch

Signs of Worn Fan Clutch
Signs of Worn Fan Clutch

According to Hayden, here are some signs your fan clutch might need replaced:

  • Fan spins excessively when engine is stopped (three or more times when hot engine is shut off).
  • Poor A/C performance at idle or low vehicle speeds.
  • Fan speed does not increase when engine is hot.
  • Fan speed does not increase until engine is excessively hot.
  • Fan blade tip moves more than 1/4-inch front to back.
  • Fan turns roughly or does not turn at all.
  • Excessive fan noise at all speeds due to failed bearing.
  • Vibration that increases with engine speed.
  • Leaking fluid or oily build up around the bearing or thermal spring.

Thermal spring problems can occur when the bearing is seized or has excessive play, or when the thermal spring is worn or loose.

If you’re noticing your car hesitating or stalling when driving, it may be time to replace the fan clutch. This can be done by following these steps: armed with this information, you can identify a bad fan clutch and replace it with the proper aftermarket option.

How are the valves controlled?

How are the valves controlled?
How are the valves controlled?

The two main types of clutches are fan and belt-driven. The fan clutch is non-thermal, while the belt-driven clutch is thermal or electronic.

centrifugal force pushes the fluid against the valves, which opens and engages the fan at low rpm. As rpm increases, centrifugal force closes the valves and keeps oil in reservoir. This disengages fan

Thermal fan clutches use a bi-metallic spring to sense temperature. When the engine is cool, the fan is disengaged. As the temperature increases, the spring rotates the valve plate and allows air to flow through it. This engages the fan. As the temperature drops,the spring relaxes and rotates back to its original position stopping airflow

There are 4 levels of thermal fan clutches:

Standard Duty Thermal Fan Clutches

When the fan is engaged, it should be turned at 50-60% of the water pump speed.

Heavy Duty Thermal Fan Clutches

When the fan is activated at 80-90% of the water pump speed, it provides more airflow for better cooling.

Severe Duty Thermal Fan Clutches

The fan on the water pump runs at a slower speed when it is engaged, which helps to keep the pump cooler and last longer.

Electronic Fan Clutch

A thermal clutch operates similarly to a mechanical clutch, but the valves are controlled by a signal from the vehicle’s computer.

A clutch fan is always engaged, even when it’s not needed. Even when disengaged, the fan will turn at 20-30% of the water pump speed.

Which type is the best?

Which type is the best?
Which type is the best?

The fan clutch is a key component of your car’s cooling system, and choosing the wrong one could result in problems.

A thermal clutch can be an effective way to improve cooling, but it should not be replaced with a non-thermal clutch. Heavy duty or severe duty clutches are better choices if thermal replacement is desired. Electronic clutches should only be replaced with another quality electronic clutch.

F.A.Q about “how does fan clutch work”

What temperature does a fan clutch engage?

Most fan clutches engage when the air temperature is around 180-190 degrees Fahrenheit (about 70-75 degrees Celsius). They will reduce the temperature by about 20 degrees before disengaging.

What controls a fan clutch?

Most fan clutches use a silicone-based oil to help the fan spin. The oil is held in an internal reservoir when the fan is disengaged. To engage the fan, internal valves open and allow the fluid to fill the working area of the clutch. This creates friction between the drive plate and housing, which causes the fan to turn

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Should a fan clutch spin freely when cold?

If you experience any of the following problems with your car’s clutch, it may be a sign that there is an issue with the fan and/or the oil: The clutch may not engage properly when you start your car; or, oil may leak from the fan and cause it to spin freely. If either of these things happens, get your car serviced as soon as possible.

Can you drive with a bad fan clutch?

A fan clutch can sometimes cause the engine fan to become loose and wobble. This wobble can be heard when driving, especially at freeway speeds. You can turn on your car’s engine while the vehicle is in park or neutral, pop the hood, and see for yourself that the fan is wobbly as it spins.

Can a bad fan clutch affect performance?

A decrease in performance can be a symptom of a bad or failing fan clutch. If the fan clutch does not disengage the fan, this can cause increased engine noise and decreased performance.

Should my fan clutch always spin?

If the fan doesn’t spin, it may be due to a bad bearing or clutch. If the fan spins slowly or not at all, this could be an indication of a problem with the motor

How stiff should a fan clutch be?

If you let go of the fan, it should start spinning quickly back up. If the fan spins very slowly after you release it, then your fan clutch might not be working properly.

Does the fan clutch affect the AC?

A bad fan clutch can cause air conditioning issues. The condenser needs airflow to cool hot refrigerant.

Is a fan clutch necessary?

The fan clutch is one of the main parts of a cooling fan’s operation and helps control the fans. Many newer vehicles use electric cooling fans, but many older vehicles still have a mechanical fan clutch that helps to regulate the speed of the fans.

How do you adjust a fan clutch?

How do you test a radiator fan clutch?

If the fan does not spin freely when the engine is off, there may be a problem with the clutch. If the fan wobbles when rotated by hand, then it is likely that the clutch is bad.

Will a fan clutch tighten itself?

The paragraph will tighten itself down just fine.

There is no need to worry about the paragraph tightening itself down; it will do so on its own in due time.

Will a bad fan clutch cause no heat?

A fan clutch can fail and cause the fans to stop working at their full potential, which can lead to an overheat

Can a fan clutch be repaired?

In most cases, it is best to replace the fan clutch. If your engine overheats or heats up due to a lack of cooling, the fan clutch may not be working properly.

What does a bad fan clutch sound like?

If your fan clutch is not working properly, you may experience a loud engine noise whenever the car is cold or hot. This can be very disruptive and annoying.

How long does it take to fix a fan clutch?

Replacing the fan clutch on most vehicles is a quick and easy job that can be done by anyone with basic tools. You will need to provide the make, model, and engine size of your vehicle for an accurate estimate of labor required.

How much does it cost to fix a fan clutch?

Fan clutches can range in price from $75 to $200, but labor costs will add an additional amount to the cost of replacement. When labor is factored in, the total price for a fan clutch replacement can range anywhere between $285 and $500.

Can a bad fan clutch cause transmission problems?

A potential issue with your trans could be the fan clutch, which can overheat and cause late shifts or no shifts. You should check the coolant level and radiator fluid levels in order to determine if this is the problem.

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Will a bad fan clutch squeal?

If the fan noise you are hearing comes and goes when you turn off the AC or heat, it is likely your clutch.

How do I know if my viscous fan is working?

If your car’s engine is hot, you should be able to hear the fan kick in. If you can’t, pop the hood and turn off the car while watching the fan. If it comes to a stop gradually or stops altogether, then the fan hub is probably working properly.

How do you unstick a fan clutch?

What’s the difference between thermal and non thermal fan clutch?

A non-thermal clutch operates by using the speed of the water pump to engage the clutch. This type of clutch offers lower fuel savings than a thermal-style fan clutch, but is always engaged, so it provides a steady flow of cooling air.

Should a viscous fan spin freely?

If you flick the switch, the fan should spin more freely because the fluid is warm and has a lower viscosity.

Can low coolant cause fan to not work?

If your coolant level is low, the engine may not feel as if it’s getting cool even with the radiator fan turned on and working. If you don’t replace your coolant level when it’s low, this can cause the engine to become seized.

Is a clutch fan better than a regular fan?

When it comes to fans, clutches are less efficient than electric fan motors. These benefits include better air flow, improved fuel economy, cooler engine running and increased engine power.

Can you lubricate a fan clutch?

The bearings that support the drive shaft for this clutch are regularly subjected to high temperatures. Krytox lubricants have low volatility and high viscosity, which helps to provide long life and excellent lubrication to the fan clutch bearing under these conditions.

How do you adjust a fan clutch spring?

What temp does a viscous fan kick in?

If you notice your vehicle is overheating or running hotter than it normally does, listen for the radiator fan to activate. The fan should kick in at around 200 degrees Fahrenheit.

What does a cooling fan clutch do?

A fan clutch is a thermostatic engine cooling fan that can freewheel at low temperatures, allowing the engine to warm up faster. As temperatures increase, the clutch engages so that the fan is driven by engine power and moves air to cool the engine.

Why is my car fan wobbling?

If there is any wobble or play in the fan, it may mean that the fan clutch is worn or a bearing on the water pump shaft is bad. Replacing either of these parts will usually fix the issue.

What are the signs of a bad water pump?

Five Signs Your Water Pump Is Failing
  • Overheating. A dead or dying water pump cannot circulate coolant through your vehicle’s engine and, as such, the engine will overheat. …
  • Coolant Leaks. Coolant leaks from the water pump are common and a clear sign that it’s time to replace the pump. …
  • Corroded Water Pump. …
  • Whining Noises.

How Does a Viscous Fan Clutch Work?


The fan clutch is an important part of a car’s engine, and its function can be easily explained with a little bit of understanding about how a fan works.

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