Looking at an ice machine today, very vague i know but, checking sh and sc off the chart so to speak sh about 40-50 subcool negative 40-50. Way udercharge Im thinking so I add bout ten percent of factory charge along the way hoping to see sh come undercontrol and sc get positive. no, was able to get superheat lower and lower with additional charge but sc still in the neg 30 range. I said compressor at first but now im thinking hot gas by pass leaking....because txv should have limited superheat yet I was able to get it below five.. I did this, I think by forcing more refrigerant into system around the txv if it were not the hot gas bypass then txv should have controlled superheat instead it was directly proportional to charge. Is this correct ? I know its probally easier to just check delta t across valve but I left befor I could think of that.