Nitrogen pressure testing questions

[rgnprof]

I am fixing the AC on my 1993 Ford E350 chassis motorhome - going back with R12 (since I have it). I have replaced everything - all new parts as my old FS15 compressor black died on me! Bought a new compressor online (Amazon) and it froze up on me during my first try at recharging. Not sure what happened as I was charging vapor only through the low side and once the compressor starting cycling on and off, after just a minute it started smoking and locked up on me. I got things shut down pretty quickly, pulled the orifice tube and it looked clean. I didn't replace the drier as I had just replaced it - hope that's alright, but a local AC shop thought I would be fine.

Bought a new Motorcraft compressor this time and just got it installed. Nitrogen pressure testing using my AC manifold gauge set and I had a leak on the hose manifold that connects to the back of the new compressor. Pulled it and re-oiled the o-rings (they looked fine) and reinstalled it. I pressurized the system to about 200psi - open the high side and then barely open the low side - then closed off both of my manifold gauges...I think I have a leak, but I'm confused. The low gauge settles at 95psi and the high side at about 160psi - they have both stayed steady now for more than an hour.

Do I have a leak? I'm going to leave it pressurized overnight - since I'm going back with R12, I want to be as sure as I can that my system is leak free! I'll run a nice long vacuum after all of this...

[bohica2xo]

How much oil did you put in the system? What kind of oil?

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