I hava a Zanussi Fridge Freezer (self defroster)which runs constanly
I think it is about 13 years old
Model No is ZD 50/17 R
Type B25741
It generates ice layer inside fridge
Rotating thermostat seems to have no effect except turning it on & off
On rotation there is no click point which should indicate temperature
Is a faulty thermostat the problem or is it deeper than that
Any help appreciated