Almost all equipment has glued inside the calibration according to the ambient temperature, if you already tried lowering the thermostat to a minimum and it does not stop freezing the food, it is clear that the thermostat is failing and you would have to change it, it could also be that wherever you go placed the bulb, that area does not have frost or is not sticking on the evaporator plate or evaporator plate and therefore does not cut the compressor, it would be a matter of reviewing those details.