Belt squealing when AC is on - 2001 Chrysler Sebring - any danger?

I have a 2001 Chrysler Sebring and most of the time when I turn the AC on, a belt starts squealing very loudly. It stops a couple of seconds after I turn the AC off. The AC doesn’t work all the time, only if I’m lucky.

All I want to know is if that belt breaks, will it effect anything other than just my AC? Will it cause anything major to happen that might really damage my engine?

Also, any idea how much it might cost to replace the belt? Thanks!