Ok...I'm starting to get annoyed with evacuating.
I use 2 appion core tools, a bluvac, appion 1/2" hoses, nylog, and jb 7cfm pump.
I switched to commercial work. When doing residential i could pull new linesets and coils down to 80 microns, valve it off and it would stop around 150.
Doing repair work on r-22 rtu's, i replace driers to correct size, pump them up with 400psi nitrogen with digicools, no signs of leaks, then pull a vacuum.
I can get my microns down under 500 but, sometimes my bluvac will read 500 then jump up to like 750-800 then pull back down. once i get under 500 for awhile i will throttle ball valves to get air out and then valve off unit. my microns will keep rising as if i have a leak. why is this happening? i just get frustrated and let it pull back under 500 and weigh the charge in real quick.
so far these units are still working and no refrigerant has been added.