Found Prep Table unit low on refrigerant, Dropped refrigerant left in system and recharged with factory amount of 134A, I checked for leaks in evaporator with leak detector and found none, I also checked for leaks at condenser and found none until I removed my gauges, found high side service valve leaking, I tightened shrader valve and the leak stopped, unit got down to temperature and cycled off,unit is working properly at this time.