Ok, so my ac does not work. Being in Phoenix, it is already starting to get hot. So I really need my AC working. I was working on a previous thread to try and resolve the issue. Since then I have read tons of AC articles and posts. So I think I know the ac system much better than I have before. Ok so here it goes:

I notice when I run the AC, it makes a hissing sound whenever it is on. From what I have read so far, that is either going to be a vacuum air leak or low freeon, gas instead of liquid hitting the expansion valve.

It makes a hiss that sounds like a combo of a tire going flat and a gas line.

Is there any quick way to diagnose which one it could be?

Random info:

The compressor, when running, has one side hot, the other side warm.

The reciever/drier is cold to the touch, including the lines before and after the drier assembly.

Would my best bet be to start looking into the vacuum system to see if it is just allowing fresh air instead of ac, or should I start looking into a recharge of freeon?

Thanks.