Bad Alternator\AC compressor??

Hello guys,
On my 01 Cherokee whenever i turn on defrosters front or back, my battery gauge drops. As soon as I turn it off it goes back up. SOmetimes when Im stopped at a light the belt will squeek when i go. Its a pretty new belt and a Gatorback. It pretty tight i checked, now could it be the AC compressor causing this or the alternator going bad? It even does it when i put on rear defroster. Could it be the water pump? Thanks!

I had a gatorback on my truck for maybe two years and it started squealing. I retightened everything and it stopped for a couple of weeks, then started up again. Simpliest solution was to take it off and replace it with a new one. I keep the old one in the back of the jeep, just cause ya never know. How old is your battery ? Have you checked the water level ? I run with an Optima Red Top, a few bucks higher then your average battery, but well worth it's weight in gold I think. Go to any service station, 90% of the time they will check the alternator and battery without a charge from your pockets. Hope some of that helps

91XJRubicXD, which belt did you end up going with? I have a Gatorback on mine, been on about the same time as yours, and under a load, it starts squeaking, I will probably replace it, just didn't know which one to go with. Thoughts??

Jeff

well, since no one wants to address the OP issue, I will. You do know when in defrost mode the a/c comp cycles. You need to put a meter on it to check alternater output to verify your guage. Anything over 14 is good , anything under bad.

The battery is fairly new probably a year old. Autozone checks it for free right? I think I remember seeing a sign. I knew the AC compressor cycled thats why i didnt know which one could be bad maybe the ac compressor is causing because it seems to do it mostly when thats on. Thanks guys

sublime600 said:

The battery is fairly new probably a year old. Autozone checks it for free right? I think I remember seeing a sign. I knew the AC compressor cycled thats why i didnt know which one could be bad maybe the ac compressor is causing because it seems to do it mostly when thats on. Thanks guys

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Simple. unplug the a/c compressor and see if it acts up? done deal.

When in defrost the compressor cycles to keep the oil in the system circulating. Also the fan puts a load on the system as well. I currently have my compressor disabled, and during the cold bouts we have been having, my extra plug in voltmeter is registering between 9 and 10 volts. After it seems to warm up, it shoots up to 13.5-14.3. Once it does this, I figger its running fine right? Well add my lightbar, and blower, rear defroster and other accessories, and now it taxes the system and I can hear the belt squeeking(which tells me that the alternator is being told to charge. It seems that the alt is sluggish in responding, but I have to check the PCM, and see if it is sending the signal for the alt to charge. Do I need to apply a load to the system to get the signal from the PCM? Or is it voltage, and if that is the case, how much voltage should I be seeing? Thanks.

Check the belt again!! It may still be loose!! I had the same problem and replaced the alt, same crap. Checked the AC compressor and all was fine there. Tured out that my damn belt was still to loose even though I though it was tight!! It needs to be VERY tight, even with a new belt!!