Hi Remi
Im a Domestic fridge repairer, this is what I think happens when a Chest Freezers thermostat is changed to cycle as a Fridge.
A Fridge known as a Cyclic/Moist Cold, which means its not a Frost Free and has in the Food Cabinet a cooling plate against the back wall, which when running or [Cycling] turns frosty, when this plate becomes cold enough the thermostat sensor that is attached to it, turns the compressor off and the plate that has a thin film of frost on it turns to water, and runs into a drain at the bottom of that plate.
Now in the case of a chest freezer, it is designed to hold its temp. at around -18 to-20 or there abouts, everything including its insulation stays frozen, if you now change the opperating temperature to run at say +4 or there abouts, it will then still freeze a section of the pipework internally behind the lining or all of it, but it will then defrost like it would in the case of a cooling plate, then that water soaks up into the insulation over and over again, then owing to that tube being mild steel with a very thin coating of copper, and sitting in moisture, it forms pit holes untill it is too thin to hold the pressure, and out blows the gas.
While they work there a great thing, but in my opinion not designed to do so for many years.
Thats my long winded opinion, but I hope it helps
Chris :icon_cheers: