So I had to do some custom work on the a/c to get it back in with a vmount. Everything is sealed up and put a 25 in vacuum on the system and it loses it in maybe 20 minutes and nothing visible or hissing around fittings.

I have the pulley parts on order, but if I put a vacuum and put some dye would it be enough pressure to locate the leak easier with a uv light?

 

When it has a vacuum on it air leaks back into it so u won't hear it or have dye really coming out. I'd pull the vacuum, charge the system with the uv dye and a cheap environmentally friendly r12 alternative that is compatible with what ever compressor oil u have in the system(or add oil if needed) and run the system for a couple min, it will probably leak pretty fast while on and u should be able to see the dye. then or hear it.

a charged system has around 45psi or so when off, but when running the high side pressure is much higher(like 150psi) can't remember exact numbers but u get the idea