Hi Guys

Would like to run through a system that i've converted from R22 to R422D.
Equipment is for a potato store that holds 2000T of potatoes. It has been in production since 1990 running on R22. Carrier 6 cylinder compressor with 3 fan air cooled condenser with fans being controlled with pressure switches. The evaporator is 3 fan floor mounted with fixed spiral ducting going to ceiling blowing across product and air returning to cooler. Off cycle defrost. Defrost every 6 hours for 1 hour. I have a list of pressures/temperatures that i have obtained

Suction Pressure 3.0Bar(g)
Suction Pipe temp at expansion valve bulb +8DegC
Suction Pipe temp at compressor +8DegC
Suction Pipe Length 6Mtrs
Superheat 13.6K

Discharge Pressure 15.5Bar(g)
Discharge Pipe Temp at Compressor +70DegC
Discharge Pipe Temp at Condenser In +65DegC
Liquid Line Pipe Temp at Condenser out +33DegC
Liquid Line Pipe Temp entering Expansion Valve +32DegC
Liquid Pipe Temp directly after Expansion Valve +11DegC
Air On Cond 12DegC
Air Off Cond 24DegC
SubCooling 8K


Ambient Temperature is 12DegC.
Air On Evaporator 11DegC
Air Off Evaporator 6.5DegC
High Pressure Receiver showing 10% Liquid Level However sight glass at expansion valve flashing.

Im guessing that the system is still under charged due to high superheat and low subcooling....would anybody be able to comment on this? I can also see frosting on about 3/4 of the evaporator. Thank you in advance