If you suspect a belt is squealing, with the engine idling, dribble a little water on the smooth backside of it. If the noise changes, one of the pulleys is likely tipped or turned due to a worn bearing. Most commonly that is caused by the spring-loaded tensioner pulley or an idler pulley. The squeal comes from the belt sliding across the tipped pulley as it goes around it, or the next pulley. It only takes 1/16" sliding sideways to set up a horrendous squeal.
If the noise doesn't change, it is possible the spring-loaded tensioner pulley is rusted tight and is failing to put the belt under proper tension. With the engine off, find a place where you can tug on the belt to force the tensioner arm to pivot. It should take pretty good force to do that, then observe if the arm moves back smoothly to take up the slack as you release the belt.
You might find more valuable ideas from these articles:
If it appears the noise is not related to the belt, check out this article:
and let me know what you find, then we'll figure out where to go next.
Friday, November 8th, 2019 AT 5:36 PM