Can anyone out there give me some feedback. Im ashamed to admit it but im having hassle along with several of my colleagues with a walk in freezer. The design conditions are -20c but i cant get the cabinet down to temperature. Ive changed the tx valve, drier, sight glass, evacuated down to 2 milibars and still no luck. It seems to hit a barrier at around -4 and then slowly gets down to -10 overnight. Never any lower though???
Ive selected the correct valve and orifice size left the superheat setting to 6k which the manufacturer assures me is correct and im running at a back pressure of around 12psi -14c.
Im pretty sure the system has the correct charge and theres nothing wrong with the cabinet seal or compressor valves.
Is there anything left?? Or is all this insanity so logical???

Any help appreciated