Either it's too loose or you need a new belt.
Change the belt
Check you serpentine drive belt and pulleys.
serpentine belt loose
Water from the road has splashed up into the engine serpentine belt causing belt slippage that makes a squealing noise. The sqealing is one of your engine assessories that use the serpentine belt to drive it.
it could be a serpentine belt or accessory belt.
Worn serpentine belt and/or belt tensioner.
I need daigram of 2001 ford focus se serpentine belt
sounds like you need to replace the serpentine belt
Possibly the wrong belt was installed or most likely your belt tensioner is bad.
How do you put on a serpentine belt on a 2002 Isuzu axiom
Replace the belt.
Your serpentine belt is loose or worn.