Your vehicle's engine makes a lot of heat when it's powering you down the road, so it needs a way to get rid of that energy.  That's why your vehicle has a cooling system, complete with a radiator and one or two radiator fans, also called cooling fans.  Those fans make sure air keeps moving across the radiator so that the heat stored in the coolant can be dissipated outside when the vehicle is stopped or not traveling fast.

Radiator fans can develop problems and can stop working properly or stop working altogether.  Some signs to look for? If you're driving slowly and idling and you see your temperature gauge moving toward the red or hot zone, that could spell trouble.  Another thing you may notice when a radiator fan is failing is that there may be a loud noise coming from the engine compartment.

There are two types of radiator fans.  One is mechanically connected to the engine and uses the engine's rotational energy to turn it.  The other is an electric fan and is the type used in most newer vehicles.  In the electrical type, one of the components, such as a relay or fuse, may fail, causing the fan to stop turning.  In the mechanical type, since it's driven by a pulley/belt mechanism, one of those components may break or stop working properly.  A clutch can wear out or a belt may slip or break. 

When your cooling fan isn't working properly, it may cause your engine to overheat which could lead to expensive damage. That's why it's important to make sure you visit your service facility if you notice any of these symptoms.  A technician is trained to diagnose the problem and make sure your radiator fan is doing its job.  When it comes to your vehicle, your radiator fan really is your biggest fan.