No or less cooling performance on all sources

In case of a no or less cooling performance on all sources please perform this important test:

Do the thermistor check: the thermistor is on the 5th cooling fin from the right in the refrigerator. Follow the wiring upwards and disconnect the two plugs. Please note that now the fridge will go into error mode (blinking display or a wrench symbol with the number 13 next to it): this can be ignored, because this test causes this error modus!

Keep the thermistor disconnected like this for a least 3-4 hours.

If refrigerator starts to cool properly, then either the thermistor needs to be replaced (part number 623077) 

Or

Check the clip that holds the thermistor on the cooling fin. 

There may be some corrosion/dirt/scale on either clip/cooling fin under the clip. Cleaning/gently sanding with fine sanding paper can massively improve the conductivity (improving the cooling performance!)