Model 561 RFDF This sub zero unit has two separate compressors. The freezer compressor works fine. I noticed that the refrigerator compressor was running continuously, and would only cool to 40 F. There was ice build up in the rear of the refrigerator near the evaporator coil area. I turned off the refrigerator to let the ice melt. When I started the compressor again, it would only cool (? 75 in room) to about 60 F. I checked the compressor with a gauge, and it would draw down to 0 psi ( Should be at least 9 psi.) while running. When turned off, it would show its normal pressure of 39 psi after about two minutes. I was told that the compressor has a leak. If so, why does the normal pressure of 39 psi show after turn off? (It does not go away. Still essentially at 39 psi after overnight.) Is the compressor contaminated, and needs to have a vacuum pulled on it and recharged, or does the compressor really have a leak? Where would the leak most likely be, the evaporartor core, compressor, or associated parts? What technique is best to find leak? The first time the leak took 10 years to show, this time (?) two years after recharge. Can everything be gotten to without having to pull the unit out of it installed place? ( Not an easy job in itself.)

Not sure about the type of pump you have... but I hope to work on those units... nice stuff. My educated guess is that it's a rotary pump. The displacement on those small pumps usually are higher than some commercial equipment. If the reeds are off by as little as .0005" you could have a failure; however, you might just have a plugged drier and a rotary not a piston type... Does the compressor feel cold on the bottom during the run cycle? How about the dryer's temperature? Most likely there is no leak. Remember refrigerant is absorbed in the oil... So, if your charge wasn't weighed in and you are getting migration on the off cycle its possible that you redefined the pour point (so to speak) and the oil is your problem... interesting isn't it? Make sense now?

Suck the unit down and put a small trap on the suction line. Then change the drier, and recharge with new oil, and freon weighed in.

Unless your not certified, then check thermistors if the box has 'em.