So, I'm nearing the end of the A/C rebuild, and I can't seem to get the system to hold a vacuum. I can get it up to 25inHg of vacuum with my pump now, but when I close the valve, it leaks back down to 0. I connected and torqued the connections to spec. (I had to guess on the connections with too little space to permit my beam wrench.)

I have attempted to locate the leak by stethescope, but that didn't get me very far. I added UV dye, so once I get it close to sealed, I can use that to find any slow leaks, but I need a method for the current state. Obviously, if I had access to dry Nitrogen, this would be a non-issue, but I'm not ready to pony up $120 for a regulator.

Any suggestions for locating the leak that doesn't involve venting large quantities of R-134a into the atmosphere?

Thanks in advance.

 

You can add a very small minimal amount of dye-containing R134a to pinpoint the leak -- no need to add a lot.

 

Yes, but the R134a will escape rapidly through the leak - and I will probably resort to that, but I was looking for a more elegant solution.

Should I replace the drier *again* because the system was not been completely sealed when I installed it the first time? (After all of the leaks are located, of course) Or, should I wait to see if there is a moisture problem?

Thanks