I have a 2001 Sonata. I have a squeeling pulley.
It sounds like you have a worn or streched belt making the sqeeling noise. Whenever you turn on a
device in the car that draws a fair amount of voltage
ie. a/c or headlights it will cause increased drag on
the alternator and if you have a loose/worn or glazed
belt, it can slip around the pully making the squeel.
To adjust the alt-a/c belt loosen the mounting bolts
on the tensioner, then use the adjuster bolt behind
the tensioner pully to loosen and tighten the belt.
Be sure to check the belt for cracks bald spots etc.
While the belt is loose spin the pullys to make sure
they all spin freely. Also I would replace the belt just
to be sure. Hope this helps