97 wrangler battery not holding charge!!!

I have a 97 jeep wrangler 4 cyl. and the battery won't hold charge!!! I had the alternator checked it was fine. I also switched batteries and it did the same thing!!! Today i started it up, and the meter was reading half way then i turned my heater on and the belt started sqeeking really bad and the battery meter started dropping, when i turned the heater off the belt stopped sqeeking and the gage started climbing again!!!! Please help!!!!!

Look at your A/C compressor. When you turned on the heat, do you mean the defroster. This (defrost mode) turns on the a/c compressor, you might have a bearing failing in the compressor that would only be noticed when you engage the compressor, causing a drag on the belt, there fore, belt sqeal, slowing your alternator down, volt dropping off.

Also sounds like you need to tighten your Vbelt, if it's squealing there's some slippage there. Once you've done that, monitor your battery and see if it stays charged.