Well the leak detectors do work to show where you leak is if its like my compressor belly leak you will probably see some pag oil below the compressor and hear a hiss after the system has been off for a little while. The compressor is a few hundred to buy and replace im going to rebuild mine next week and I plan on making a tutorial out of it, my compressor leaks out of the middle cylinder seal when the pressure is equalized when the system is off

 

I recharged it yesterday with about 2 lbs of r134a. Working pretty cold now which is good news. I did get the leak detector, glasses and light too and went through that whole process. I couldn't find any leaks though. Maybe it got plugged up by dirt or something, I dunno, but lets see how long this filling lasts.

BTW, you really don't need the glasses and flashlight, it's not too difficult to see the leak detector unaided.