Last week the thermostat packed up. I called out a local appliance repair firm and they changed the thermostat. However, even on its warmest setting it ran too cold - the freezer was at least -24C and the fridge compartment was too cold: the water in the drain gutter under the 'cold plate' on the fridge rear wall was frozen.
Today they came to replace the new thermostat, but it seems that the it was not faulty because the same thing is happening with this second replacement thermostat.
I have dismantled the original, failed thermostat and notice there are 2 adjustment screws and 3 contacts. I notice that the middle contact is connected to one of the outer contacts at all times unless the thermostat is turned to Off, and that the 2 outer contacts appear to make and break depending on whether the sealed bellows has triggered them. I can't figure out why there are 3 contacts, though and there's no circuit diagram. But I imagine that the 2 factory preset screws control the temperatures at which the compressor comes on and goes off. I'd be grateful for some advice on how these thermostats work and how best to go about tweaking the screws.
(Is there a heater in the fridge 'cold plate' or does it defrost naturally during the compressor off part of the cycle?)
Any clarification of the functioning would be much appreciated.