Walk in freezer ice cream not completely frozen

Hello my friends first time so i am a little green at this. Here is my issue wondering if u can offer any help. Tempatures inside box was only coming out at about 10 degrees. have a walk in freeze on second floor of building compressor is a Copland cs14k6e-pfv-270. Txv is a danfoss model Tey268z3285 -40 r502. Box size is about 6 feet by 8. Been there for awhile. Originally had r502 replaced to 408 refrigerant and changed filter tempature were coming out -20 and thought done. Well same issue. Box was still only at about 10 F degrees two days after. So I checked my superheat ambient tempature was at 70 f degrees. Low side pressure at 40 psi line temp at 25 so superheat is ten. Good . So when I put temp at front of evap fan I get -23 f Return temp is 2f degrees. Nothing blocked coils are clean at cond and evap. Pressure at cond low side 45 high side 165 any clues checked defrost timer in case it was getting stuck nothin.

Notice recent exhaust fan installed i asked for what they said to keep air around both walk ins dry they also had handyman seal of all corners due to mold build up. Was running this way for several months told them to shut this off for time being don't want pull in hotter air around walk ins. But it is solid 4 inch walls built up and tight.

hi grrr,
I have 3 questions =
what is your native language ?
where is oc?
did you remember to shut the freezer door?
regards sedgy,

I don't see how you could have an air off temp of -23F with a suction pressure of 40/45psi as this temperature would be about 22psi.

Is the compressor pumping ok?

Whats the air on and off temps for the condenser?

Subcooling?

Defrost heaters stuck on?

Internal leak on suction/liquid heat exchanger?

Txv leaking down equalising line?

Are all the u bends on the evap equally frosted?

Correct refrigerant?

Is the run current high or low compared to the data plate?

Evap fans all running the correct way?

0 degrees is the setting on the tstat on off temps compressor running good it's about 4.3 amps while running. Defrost heaters are not stuck on. Thought that there was a leak in system but hasnt been real temp change in the past couple days and reading is still the same had my leak detector out electrical one and the liquid leak detector not losing refrigerant. Yes all u bends are lightly frosted and it is the correct refrigerant 408. Is a direct replacement for r502. And fans are running correctly. Will need to check on data plate for exact but I believe it was slightly under by a couple amps. Boss says to Chang out txv but I don't think that is the issue. Still investigating.

Yes and to the response of the gentleman from Spain yes the door is closed and I speak three lanquages but primary is English. And I did not use spell check sorry if I was hard to understand thanks for the help.;)