It sounds very much like the evaporation fan has stopped working.
I have had the same problem & will tell you what I did to mine & it still working now.
If you are not sure of what you are doing, please seek a professional.
I took everything out of freezer after unplugging it, found the screw hole covers & took them off. (2 plastic things) come off easily with a small flat screwdriver, then took out the 2 screws.
The bottom of freezer comes out revealing Styrofoam insulation, coils that the fan blows on, & the fan.
I plugged it in to see if fan was working & of course no it wasn't, unplugged it & unplugged fan from inside freezer, sprayed it with some lithium grease that was made to be okay for electronics.
Cleaned the blades & around it with warm water (hot), plugged it back in and into the wall to make sure it was working. It actually took a few minutes of spinning it & stopping it to make sure it would start on it own.
Put it all back together & it has been working for 8 months now with no issues.
I do not recommend anyone to use this method but it worked for me.
Good luck.