do all the alternators whine or is it the alternator
Not all, if it does, then the bearing might be worn out. Remove the serpentine belt and spin the pulleys by hand, see if one makes noise or is rough turning. Also a free spinning one is also needs to be replaced.
Could be normal. When under heavy load (headlights, rear defogger, blower on high, etc.) some alternators will whine. Not super loud, but audible. Most of my GMs have done this. If it's loud though, then it's the bearings inside of the alternator. HTH. -Jim
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