Refcomp SRC-S-182 oil trouble please help.

[fridged]

Hi guys, I have been working on the above mentioned chiller unit.
Basically it has had pressure test,leaks repaired and an oil change, filter change.
Everything has been going to plan until today we charged with the correct amount of R407C.
When we came to run the system it started up fine and straight away the back pressure down to 0.5 bar.
Didn't move and the unit went out on low pressure.
After a check to make sure all valves etc were opened, (they were) I removed my suction line gauge to find oil pour out of it, I know its common to get maybe a bit of oil but this poured out. I put it on and then off again and it was full again.
After isolating the compressor and removing the refrigerant from the I then proceeded to drain a hell of a lot of oil from the motor drain off nipple.
Now I know there is no way that much oil should of come from there. Vacced out the sytem again and the problem of 0.5 bar is still there.
1, Is this a problem with the oil that is causing the low back pressure ?
2, Why the hell is so much oil in there?
3, WHAT DO I DO NOW ??????
Is it a case of emptying the system again and striping it down or has anybody come across this type of thing before ?
Any info much appreciated >

[GHAZ]

hello fridged some screws have built on oil seperators but when they are short of gas the oil gets pumped out and the engineers keep filling the compressor up with extra oil,check you expansion valve

[fridged]

Cheers for your response I am unable to say wether that has been the case.
If that is the case what is the next step ? Is it going to be a case of draining the oil from wherever possible and just hope or do I need to strip the compressor and clean it out....???

[RCassist]

Hy Fridged,

I think you've already gone through it, as your post is old. At least I hope so. Anyway, if it helps, I can tell you that a lot of R407C systems are suffering from the same problems. Especcially those that have S&T exchangers, which internally riffled tubes. Due to the wide spread on R407C between beginning and end expansion temeprature, it often happens that the superheating in the heatexchanger is too low. This is carrying over oil from the oil separator, due to the foamed oil-refrigerant mixture. This oil gets trapped into this riffles, and when you are reregulating your system it happens that hte additional oil previously putted into the compressor comes back. The only solution is drain it with patience. But i suspect you've already done it.