usually it is a loose belt
Depends on the nature of the screeching sound. Most often it's a loose (slipping) belt. Tightening your drive belts (or if old and cracked) replacing them should fix it. Sometimes belt dressing works (check your local auto parts store)
There are two probable causes. Assuming you are talking about a car fan, the screeching can come from a mis-alignment of the fan withing the cowl or shroud that conducts air to and from the fan. If you are talking about a home HVAC unit, the screeching probably comes from a slipping drive belt (or a tired hamster).
Accessory drive belt and or belt tensioner.
Assuming it is screeching in the area of the belt and pulleys, my problem was that the belt tensioner had seized and needed to be replaced. Noise problem was solved.
whst causes screeching sound when i turn the key in my car?
good chance the fan belt is slipping when driving may need tightning up this wouold cause a screeching noise.
Fan belt slipping?
A slipping drive belt is one possibility.
you have a small cat stuck under your car
I am no expert, but I believe that this is usually caused by the fan belt slipping.
Burning rubber, or screeching the tires, and then accelerating.