Beko CDA653FB/1 Fridge Freezer- Running Too Cold

As above i have the Beko cda653fb/1 from 2010. All had been working fine then my wife said the fridge was freezing food. I didn’t really look in to the problem to much but the compressor was always on and the general thought i found online was to change the main control pcb, im guessing due to the relay sticking.
Well i changed that but i am still getting the same problem. on further investigation i found the 46kohm POT which does change its resistance when the thermostat knob it adjusted (10-46) so i think i could safely say that is ok.
What would really help is a wiring diagram but i can not find one online.
On checking the main pcb, on the right hand side of it i have two plugs-KN3 and KN2. KN3 seems to be a thermistor which does seem to alter as the temperature raises. on KN2 two of the four wires go to the pot in the fridge and the other two i would think is a thermistor but i only get it as open circuit.

So can anyone tell me if this open circuit is actually the evap temp probe or some other probe as this can only be the reason the compressor carries s on running in my view?

thank you for any help given.

p.s i have used a plug time clock to turn the fridge on/off every half hour for the moment to help matters- after reading that on this forum!