A chiller we have been working on this week....It had problems. We were told by the technicians on site that it was "losing oil" as there was no puddle on the floor we deduced that it was in the evaporator and logged. The high approach and slightly lower back pressure suggested this. Discharge superheat looked OK at 22degrees F. There was no charge of refrigerant in the machine, oil was at the bottom glass on the sump. We evacuated the machine and left it standingwith a Torr gage on there. Then we were instructed to run the machine. I know that the charge removed was short (by at least 100kg). Others had leak tested the machine and so we put in new refrigerant (R123). Got the oil halfway up the second glass and thought we would run the machine up to full load and get the oil back, then adjust the levels etc until all came back to normal. Machine started up, and then after a while pumped the oil from the sump. We had all sorts of problems getting any oil back. Initially we did seem to be having a little bit of luck at full load, but that was short lived. The refrigerant in the cooler was very flat with foaming and not really any of the usual effervescence, so I know we have a heat exchange problem and then only a 4 degree C TD on the chilled water confirms this. Then we noticed the refrigerant had turned a muddy brown color and noticed rust in it, so the inside of the shell must be rusting. It turns out that the chiller had been left opened up after a rebuild a while back. The oil pick up isn't getting oil back either. I am actually concerned that this may be a bearing fault as well, so we shut the machine down. The evap is a flooded one so how is this ever going to get cleaned up, and this rust "powder" is probably in the condenser as well, which might explain the high head pressure.... I've never seen one like this, and can't decide what to do with it..