My Minisplit Install

[jyl]

I am not sure how long this is supposed to take. My vacuum pump takes the system down to 1000 microns fairly quickly, then progress slows and it c-r-a-w-l-s down to 500 and below. From atmospheric to 500 for the whole system might take 30 minutes. Hopefully that is normal-ish.

[billybek]

If you're getting to 500 microns the system is most likely leak free.
Usually you can hit much lower than that on a smallish system so it is possible that your vacuum pump is somewhat challenged. Is the ballast valve (if it has one) closed?
Some vacuum pumps are very fussy about the oil level while operating.
500 isn't bad if it holds it for a period of time.

[jyl]

Originally Posted by billybek

If you're getting to 500 microns the system is most likely leak free.
Usually you can hit much lower than that on a smallish system so it is possible that your vacuum pump is somewhat challenged. Is the ballast valve (if it has one) closed?
Some vacuum pumps are very fussy about the oil level while operating.
500 isn't bad if it holds it for a period of time.

I think I still have purging to do on the compressor.

The micron reading doesn’t go down smoothly, it jumps around after about 2500 (like 1200, 1100, 1000, 1100, 1100, 1100, 900, 800, 700, 800, 900, 900, 900, 700, 600, etc), and while I can pull it down to 400 before I run out of patience, it will then slowly rise up to about 600-700 and stabilize there.

It only does this when I’m vacuuming the whole system - if I isolate the lines, they vacuum down smoothly and stay down.

I “think” that means there is still moisture or oil in the compressor . Maybe a couple more nitrogen purges.