Wrong temperature on control panel

[swee'pea]

Hi there!

I've got a Bosch KGU3201 frost-free fridge freezer, bought in 1997.

The freezer part works fine, but the fridge has a problem:

The temperature in the fridge is much warmer than the one displayed on the control panel. When the display shows the required temperature of e.g. +4 degrees, the cooling stops, although the actual temperature is still about +12 degrees (which is the ambient temperature).

To check, I set the temperature from +4 degrees to the lowest possible temperature (+2 degrees). The fridge worked for a few minutes (I could hear the coolant flow when I put my ear against the side) and the water droplets on the interior rear panel of the fridge compartment became frozen. But as soon as the control panel displayed +2 degrees, the cooling stopped and the frozen film very quickly thawed again. All the time, the actual temperature in the fridge was nowhere near 2 degrees, but closer to 12 degrees.

The fridge is about a quarter full and air can circulate freely. I also make sure that the area right next to the temperature sensor is kept free. The drain hole in the drainage gutter is unobstructed.The seals around the door are clean and undamaged.

The call-out fee for a Bosch engineer literally costs as much as my monthly food budget. Is there a way I can repair the problem myself? My gut feeling is that the problem might lie with the sensor.

Could you give me some advice, please?

[R. skiffington]

Not sure the specific controls on this fridge but if the fridge compartment is controlled via it's own thermostat, then it's faulty, it maybe just the sensor on the stat if it's electronic, some fridge/freezers have a thermostat that opens/closes a damper between the fridge and freezer to allow cold air from the freezer to the fridge as required. Either way, whatever is sensing the temp in the fridge is faulty. Hope this helps, I work in comercial/Industrial ref so don't work on domestic a lot.

[swee'pea]

Thanks a lot for your answer, R.skiffington. Yes, I also wondered if it could be the sensor in the fridge compartment (by that I mean the little plastic covered cylinder that's covered by a little grille; I'm not an RE expert, I used to be a mining engineer). To check, I pulled it out and warmed it in my hand for a while, then I slotted it back in. The result was the same: it displayed +4 degrees.
I do assume there is a different thermostat for the fridge, since it is possible to switch off the fridge and leave only the freezer running.
I'll try and get hold of a sensor and let you know the outcome.
Thanks again.