Could be the alternator or more likely the AC compressor. If you turn the AC off, but turn the blower to high, the lights all on high and any defrosters, does it still squeal?
Those would put almost the same current draw on the alternator as the AC clutch.
You can listen to the bearings in the alternator by using a long screwdriver or dowel rod, you hold that tight to your ear and put the other end on the alternator. A good bearing will sound like air rushing by, a bad one sounds like you are driving on a gravel road in a hail storm.
Just be VERY careful of any moving parts.
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Tuesday, September 5th, 2017 AT 8:57 AM