99 with 4 month old alternator. Driving tonight, everything was going good. Turn on A/C and volt gauge hits 9 like a rock and check gauges light pops on. Drive home (4miles) and pop the hood, turn off A/C and bring out test meter. While running, voltage registers at 13.8. Load it and it goes down to 12< then picks right back up to 13.8. Left it running for 30 mins with radio on and 2 pair of 100w lights and head lights and strobes and voltage is 13.8. Gauge still at 9.

Whats going on? Fuse? Relay?

 

could be the gauge or gauge wire circuit is faulty

 

Thanks man. I'll tear into it tomorrow. Where do i need to start looking?

 

first place I would start is with a multi meter on the wire from the alternator to the battery light circuit

 

Ok will do. Let me say this though, when ever i use to turn on the ac, i would hear this awful squealing from the engine( like the belt). After a couple seconds, it would quit, but while it was squealing the volt gauge would drop to about 11. After it stopped squealing the volts would go back up to 14.

Tonight, when i turned the ac on, it did like usual and the volts dropped a little then it started squealing, then all of a sudden it stopped squealing, the ac started working and the volts bottomed out and the light came on. But the ac still works and so does the alt.

 

sounds like the alternator has failed

 

Why so hesitant to tighten the drive belt? Takes like 3 seconds then it doesn't sound like your killing the neighbors cat.

 

Short term memory loss. Only time i remember to tighten the belt, is when im driving it or at work. Besides, i hate the neighbors cat.

 

And now the gauge works and everything is back to normal. I still don't know what happened.

 

Did it just start working all of a sudden? Or did you end up doing something to it?