I have a 20 year old Hotpoint RF60 2-door upright fridge freezer. The bottom half is the freezer and the top half is the fridge. There's only one compessor, and a single electro-mechanical thermostat in the fridge is the only temp control for the whole unit; it's sensor tube is attached to the rear of the heat exchanger in the fridge compartment.
Last week the thermostat packed up. I called a repair firm and they changed the thermostat. However, even on its warmest setting, the freezer is at -24C (at least - end of thermometer scale) and the fridge is colder than I would like - naturally, the compressor is running for much of the time but the unit does go through a cycle i.e there are times when the compressor is off and the heat exchanger in the fridge defrosts itself. However, something's not right. Yesterday, the firm replaced the new thermostat but the unit is still running too cold.
To try and understand how the thermostat works, I partly stripped the old defective one. The outer 2 contacts appear to be controlled by the bellows at the end of the sensor tube. However, there is a central contact which seems to be connected to one of the edge contacts at all times except when the thermostat is turned to Off. I don't understand what this central contact is for.
There are 2 factory preset screws which control spring tensions and I presume these screws control the temp at which the compressor contacts make and break. One's accessible on the top of the thermostat and the other's visible through a hole adjacent to the first screw. I'd be grateful for advice on how best to go about adjusting these so that with the user control knob in the middle of its scale, I have a freezer temp of around -18C and a correspondingly cool fridge.
I've tried phoning Hotpoint for help but there is no technical department. Any guidance and clarification would be much appreciated.