The Fan Clutch
Your vehicle’s fan clutch serves as an integral part of regulating your engine’s temperature. It works as a cooling device to keep your engine from overheating by engaging when temperatures rise. The fan clutch pushes air through the radiator, which then lowers coolant temperature levels. Some work based on fluid, much like a thermostat, while others are more electronically controlled. They work based on the temperatures of the engine’s oils and coolants. Some are automatic and some are fixed, depending on the make of your vehicle.
There are two types of fan clutches: thermal and non-thermal. Thermal fan clutches engage and disengage according to engine temperatures. Non-thermal clutches run according to the water pump. They do not disengage like thermal clutches do, therefore they don’t save you any money.
Thermal clutches will disengage in colder temperatures and while driving fast, like on a highway. The engine is getting proper ventilation, so the clutch does not need to engage to cool the engine. When fluid temperatures do rise, like when idling for a long period of time or if it is very hot outside, the clutch engages and silicon fluid fills the clutch body and plate. A bimetallic coil senses the increasing temperatures and causes the fan to engage. When engaged, the clutch uses fuel, opposed to when it is not engaged and uses no fuel. When the clutch engages varies between models.
Fan clutches can wear out, so knowing the signs that tell you when replacement may be needed are important. Overheating is the most obvious sign the fan is not working properly. The fan clutch is not engaging, therefore the fan is not working to cool down the vehicle’s temperature. If you are getting weak air conditioning flow in the vehicle, this is also a sign the clutch is not functioning properly because the clutch also works to cool the air conditioner condenser. Likewise, if you are only getting lukewarm heat in the winter, the bearings on the clutch may have grown weak and worn down.
Visibly, it may be going bad if the blade on the fan is loose, or you can manually spin it more than 3 times. There should not be a lot of play with the blade; you should not be able to just spin it over and over. Lastly, any fluid leakage around the bearing assembly indicates there may be a problem.
If the fan clutch is indeed bad, you need to replace it. To do this yourself, purchase a new fan clutch according to the model of the vehicle. Let the engine completely cool down before beginning. Once cool, remove the fan shroud surrounding the fan, then remove the fan itself. Unbolt the fan clutch and pull straight up and out. Attach the new clutch and reassemble the fan and fan shroud.
Make sure when removing the fan that you don’t bend any of the radiator fins in the process. This can damage your radiator and cause the vehicle to overheat.
Controlling the temperature in your vehicle is a complex process, with many parts working in tandem to get the job done. The fan clutch operates as a liaison of sorts between the radiator, water pump, and engine. Your vehicle needs all the parts in good working condition to keep your vehicle’s temperatures properly regulated for optimal performance. Overheating, temperature irregularities in your air conditioning, and leakage are all potential indicators that your fan clutch may need to be replaced.