Screeching noise under the hood

There is a high pitched whine coming from under the hood. When the car is cooled off it does not make the screeching noise but when its been ran for even just 15 mins it will start. It will screech when you start the car, drive it and even when you shut it off is continues for just a second. The noise is coming from the passenger side where the pulleys are. The belt seems fine, its not loose/too tight and its not cracked or fraying