@sonya123 The belt may be squealing because one of the bearings in whatever it is turning is going bad push down on it with your thumb to see how loose it is you should not be able to push it out of line easily.
It may be as simple as some type of contaminant on the belt too.
My old 85 3/4 Chevy has a long span on one side that lets the belt slip when I put a heavy load on the alternator like running the Trailer Winch or hooking up the Trailer Battery after it has been under load for a long time.
Hope you can find it, it will usually cause a belt to fail a lot faster when it slips.