Hello. I have a 2010 dodge grand caravan with a little over 100,000 miles and I am trying to troubleshoot a problem with the AC.
When the AC is running, I can hear an intermittent hissing sound. This has been going on for about a month. AC was cold until a couple of days ago. I bought a do-it-yourself can of freon and charged it up yesterday afternoon. The hissing went away for the rest of the day and we had cold AC.

Today we still have cold AC but the hissing sound is back. If I turn off the AC, the hissing sound goes away after 15-30 seconds.

I am suspecting that this is a possible leak but I don't know the best approach to troubleshoot it. I was hoping to get some suggestions on here. I did a visual inspection of the piping but that didn't get me anywhere.

I know there are various dyes and leak repair kits sold at auto part stores. Are those reputable? Unfortunately I have minimal tools. Thank you for your time. Any suggestions?

 

Yes, buy a dye kit and look for the leak. Unfortunately thats your only choice at the moment, other than wait for it to start hissing and then open the hood and try to pinpoint it. Good luck.

 

Might try blowing smoke in the areas and watch for a swirl. Never heard of it but it seems it would work.