Getting ready to open up store #2!
Came into an offer to buy up 8 commercial refrigerators, however i would like to have 4 refrigerators and 4 freezers.
Is it possible to convert them by installing a thermostat that allows that kind of temperature?
Will a compressor be able to make it happen?
It would depend on construction, but I would doubt it. If the compressor could get the suction pressure low enough there will be a lot of problems. A freezer needs more insulation. The compressor will probably ice over causing wiring problems.
The evaporator coils are not going to be designed for the lower temperature. Icing over the evap coils will be a problem. More ice will be on the coils at a lower temperature which will lead to problems during the defrost cycles. The drain line from the evap coil will need to be heated and insulated. If you can get the units to run at the low temp they will be energy hogs and I would doubt that the compressors will last long.
To make them work properly I would think you would need new stat, new compressors, new expansion valve, and new evaporators.
Not what you want but you may able to go freezer to frig .
To back up what Snnipe 70E said, I have 2 True GDM49 fridges, and 1 True GDM49 freezer. The cabinets look identical, but the working parts are vastly different. For starters, the freezer requires a 220 outlet, powering a 1.5HP compressor vs .5HP in the fridges. The condensing unit is also at least twice as big.
About a month ago, the temp controller in my GDM72 fridge (3 door model of the same line) fried, causing it to hold temperature well below what a fridge should. Unfortunately for me, it was able to freeze the contents (exploded sodas are no fun to clean. X10 if it’s glass bottles), but the .75HP compressor was really being overworked which was evident in the amount of heat coming from the bottom of the unit.
I did try that with a freezer. The problem was the lack of a fan, even with the sensor in the middle of the freezer it could be much warmer at one end than the other. I don’t think cycling the compressor with a simple mechanism works very well, they are probably optimized for much lower temperatures.
Some walk-ins can be converted back and forth, the ones I know of have a separate cooling unit that the temp can be set on and the interior of the box is cooled just from the fan in the cooling unit.
Have you tried putting it in Alaska? That works for me.
…are…are you me???
At this moment I have an identical set-up and same problem about a month ago.
If you are me, maybe we can hang out some time 
It has to be possible, or this wouldn’t exist.