My 97 Grand Cherokee won't start- is it b/c the AC leaks?

My grand cherokee died about two months ago and I put a brand new battery in it because I thought that was the problem. I was stupid though because it still would not start after that. I brought it to a mechanic and he kept it for over a week and said it started the whole time he had it and couldn't find a problem. Well I used the AC all the time and it leaked which caused a puddle by the penger floorboard. Mechanic said while he had it the AC wasn't being used, which is why there was no puddle. He said it's possible the leak caused the car not to start. So I have had it working fine since then until just now. I have been using the AC (yes, stupid on my part, but I live in New Orleans...) and the puddle is back. Today my car wouldn't start. Should I trust the mechanic that the puddle is the problem? Pay $800+ to fix the AC so it won't leak? Or is it possible that it's something else? Oh, it's definitely not the alternator or starter he said also. Advice is appreciated!