The fan belt in your car is most commonly going to be a serpentine belt that provides power to your cooling fan, air conditioner, power steering, alternator and water pump. Occasionally, some vehicles are equipped with two serpentine belts that share these tasks. Fan belt noise can be a sign that your vehicle's serpentine fan belt will soon need to be replaced or needs to be adjusted, or can even be a side effect of an improperly replaced belt. Fan belt noises, primarily exhibited as variations of squealing, are caused when your belt is not properly installed or is worn out and begins to physically glaze over as it slips on the pulleys.
The website 2 Car Pros recommends changing your vehicle's fan belt every two years or 25,000 miles. If your fan belt has been on your car longer than this, there is a good chance it has begun squealing because it is stretched out and worn out. Belts have a relatively short life span in terms of car parts. Once they begin to wear out, the squealing is a sign that the belt needs to be replaced.
A broken, loose or otherwise out-of-balance belt tensioner will put the incorrect amount of pressure on your belt and cause the belt to begin to squeal. The belt tensioner is also to blame if the fan belt periodically comes loose from the car.
Moisture can cause your fan belt to squeal, especially if the moisture gets between your belt and the pulleys or belt tensioner that hold it in place. If you notice your belt squealing minutes after you drive through a large puddle or in the rain, chances are your belt is getting wet somehow.
