alternator noise

I replaced my alternator and battery at sears about a year ago. Lately the alteranotr makes a noticible high-pitched whining noice at any thing above idle. Is this normal. there seem to be no other problem. I had sears check the charging system and they said the charging output was correct.

My alternator made that same "high pitched whining noise" for about a week, then it died...........

Check the idler and the tensioner pulleys also - often it. If the front bearing is whinning see if with the belt off (to test the pulleys) if and play and grating in the front bearings.