Hi Everybody! I'm working on an ammonia system that we use to condense CO2 vapors. Two years ago I put a new compressor and motor on, been running great since then. Til now, that is. The plant operator called me because of low suction pressure shutting him down. Went down there and verified the suction valve opened on startup, ran to the computer and saw suction pressure dropping into a vacuum. Evaporator showed 45% level. Impossible, right? Right! there was in fact no NH3 in the evaporater because oil from the harvester had screwed up the level controller. So I cleaned that up, got a level in the evap. and running again. Plant guy going to drain oil harvester more frequently. While I was out of town, he called to say we're losing alot of oil. Told him I can't get back so call in service guy and change out coalescent filters, which they did.and added oil. One week later all the oil from the reservior is in the evaporater.Very little oil in the siphon pot, so I don't think it went out the discharge. Got a look at the piping diagram and figured that the oil is going out the economizer port thru the (bad)check valve every time he shuts down(twice a day)right into his receiver. Check valve looks OK but I got a new one coming monday. There was a bunch of oil in it too.Anybody out there ever have this problem? My boss is not convinced.