During a rooftop unit maintenance yesterday the restaurant owner asked if i could check 2 prep tables refrigerators that were not cold enough(2 evaps on one condensing with LL solenoids valves mounted in pump down). I checked pressures at condensing unit(205/68); I checked the superheat 12 inches before the compressor suction rotolock valve and it was way too high; around 40; with both lls opened; subcooling-13f; took the amperage 6.2 out of a 7.25rla(i dont have the sst/amps chart). I had no access to the fridges because the kitchen area was crowded with people working. I decided to check if the compressor was pumping by attaching a gauge to the service port of the suction rotolock valve and frontseating the valve to see if the compressor pulls down to 5 psi. Not sure if i am right on this.... The compressor pulled from 70 to 40psi rapidly but never went below 40psi. Is it the compression ratio that is important or all hermetic compressors should be able to pull safely at 5 psi??? Tecumseh told me that if there is at least 100 psi between suction and discharge the comp is ok; how would this work with a pumped down system?