We have a york water cooled chiller with a flooded evap. The problem has been that its experiencing high discharge pressures. So far we have cleaned the pumps,strainers, cooling tower and even punched the tubes. This had no help on the head pressure which is running 74/252. We decided that the unit might be overcharged and his would also explain the the loss of oil in the seperator. We removed about 40 lbs of r22. The end result was pressures of 52/233. the head pressure dropped some and now we are going out on low pressure or a bad evap sensor. Slider valve only opens up to about 76% and we are running 100% motor amps. Any suggestions on what could be happening? I think we need to check the flow orfice but the boss don't. Please help. Whats the correct way to obtain your superheat. If anyone has a tech manual on this screw unit i could really use it. Thanks