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defroster and battery voltage...?

MahnkenVille

NAXJA Forum User
Location
Liverpool, NY
I had a pretty dry-rotted nasty old defroster (AC Pump?) belt so I had it replaced. About a week later the squeal came back so we were going to meet up to have it tightened again but haven't gotten around to it. Tonight I noticed with the defroster on, it will start to squeal, voltage will drop on the gauge from 14 to like 12 and everything will dim, and then will return to 14 and normal when the squeal stops a few seconds later. It did this about 3 times tonight, usually when stopped. It has been raining all day, if that changes anything, but i've seen it happen before.

What does the defroster have to do with the voltage? Is something besides a loose belt causing this drop?

Thanks,
Greg

97 XJ 4.0 AW4 231 191k miles
 
What does the defroster have to do with the voltage? Is something besides a loose belt causing this drop?

Selecting defrost also turns on the A/C. The squealing is caused by your serpentine belt slipping or not turning. The drop in voltage is because the belt is not turning the alternator.

Get somebody to sit in the driver's seat and recreate the situation while you observe the clutch on the A/C, the alternator and the belt. Something isn't turning the way it's supposed to.
 
I have been having this problem lately and had recently had my belt replaced with a gatorback belt. I tightened up the tensioner yesterday after reading that a loose belt could cause this to happen and it seemingly fixed the problem.
 
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