A cooling fan switch is a component of a vehicle’s engine cooling system. It is typically used in conjunction with an electrical cooling fan assembly.
To keep your engine from overheating, liquid coolant is circulated through the engine block. There, the coolant absorbs heat before it is pumped out of the engine and into the radiator. Air passing through the radiator allows the heat to dissipate into the atmosphere.
But air does not pass through the radiator when your vehicle is not moving. Therefore, a fan is used to move more air across the radiator cooling fins.
And yet, the cooling fan is not always needed. It only needs to turn on when your engine reaches a certain temperature. Mounted on your engine, the job of the cooling fan switch is to sense engine temperature and turn the fan on and off as needed.
In order to ensure that your engine operates within a designated temperature range - usually somewhere between 185-220 degrees Fahrenheit - the cooling fan must be operational. The cooling fan switch is the component that operates the fan on many vehicles. When the switch goes bad, the fan will either work intermittently or fail to work altogether.
If the coolant fan switch fails, your engine can overheat. You might see the temperature gauge rise or a temperature warning light come on. Your engine might run sluggishly as it goes into “limp mode”. And the check engine light might come on.
The replacement procedure for the cooling fan switch differs from one vehicle make and model to the next. Therefore, it is necessary that a technician not only procure the correct replacement part, but also determine its mounting location. The switch is often mounted on the engine block, but not in the same location on every engine. Some manufacturers even mount the switch in a radiator hose.
Once the switch has been located, any components that are in the way of access to the switch must be removed. From there, the technician will do the following:
