Apologies for the somewhat cryptic title.

I have a KGNves3846 fridge/freezer that has been trundling away pretty much fine for 10 years. Indeed I have 3 fridge-freezers (don't ask) which are all fine except for one thing - energy use on the 3846.

I am trying to be energy efficient (I know 3 fridge-freezers don't help) and bought an energy monitor. Stuck it on the 1988 unit in the garage for a month as I thought such an old unit would be a gas guzzler and it suggested about £30 per annum - obviously hot summers will use more and cold winter less but the annual extrapolation was better than I expected for a 27 year old Liebherr. Did the same on the Miele in the utility and it came out with a similar expected cost.

Stuck it on the 3846 in the same ambient space as the Miele and it seems to be sucking about 1.8kWh per day or about £70 per annum - ouch. Temperatures are fine at 5 and -18 degrees. Tried defrosting (not a lot of ice so probably not necessary) and cleaned the back (hardly any dust anyway) but no change.

Looking at the leccy monitor it looks as though the unit takes about 2.5W when just sitting there nice and cold. When the compressor turns on it goes up to about 120W just like the others but after about the same time that the others would be switching back to 2.5W or so, the 3846 throttles back to about 80W and the motor/compressor is still whirring and is hot, but not scorching, to touch. This goes on for a very long time but eventually it does turn off and leccy use drops back to 2.5W. If you were to sit and watch I reckon it could be 30-40 minutes in this mode but life is too short to do that.

I assume a thermostat, thermometer, switch, sensor or something is kaput. Anyone have any ideas please?

thanks

Gary