Found Prep Table unit low on refrigerant due to a leak at the rail expansion valve. Will get valve and return. 5/09/19 Replaced rail txv and filter dryer, Checked welds with nitrogen for leaks and found none, Vacuumed and recharged with factory amount of 134A, unit came down to temperature and cycled off, compressor valves are very noisy, compressor may need replaced in near future, unit is working properly at this time.