The plastic knobs on some Dometic fridges are very "soft", and have been known to split at the end of the shaft (particularly if turned hard against the end-stop).
The net effect of this is that they don't engage properly with the flat on the shaft of the electronic control, and thus turning the knob has no effect.
Try removing the knob by pulling outwards and turn the spindle with a pair of pliers.
If that doesn't work this may help. Cloned off the web.
Well with the help of my Apprentice Jan. we set about getting to the circuit board behind the control panel .Using a pairs of pliers I gently teased off the 2 control knobs, Now there are 2 screws where the knobs came out of, 1 in each Hole After removing the front panel (Beware the panel has wiring attached and will not come away fully). Now we can see the housing where the circuit board is located, On the front are 2 screws at each end, unscrew these and the Black box should slide forward, Ok it will not come all the way out if the wiring loom goes through the cable holder on the back of the box, so again some teasing to get the cables out of the holder, once done the box will come out enough to remove 3 screws on the top of the box. Gently lift the lid off and the circuit board is exposed, ( there is a
Fuse on this board, must remember about that if any electrical problems} now I am looking at the temp control it just turns and turns (parts are knob with long tube attached to a plastic spindle then the switch potentiometer, A rotating resistor switch) the tube end is ok, the Problem is the small rotating spindle that fits between the knob and the switch ,it has a small round end that fits into the switch and this as snapped of flush with the switch. .So I have got a new spindle and control Knob, But the switch is the problem. There is a bit of the spindle left in the switch and I am unable to draw it out, so I drill a small hole in the piece of plastic, and screw in a small screw. Yes it came out, being careful not to pull to hard and crack the circuit board. So it’s just push in the new spindle Put the 2 control knobs back on, switch fridge on, and Hey Presto, I can now turn the temperature up and down, So its cover back on, slide box back, fit the 2 screws to hold it back in place, fit the front cover and put in the screws and Knobs .
Took me 45 minutes and cost £5 plus £6.48 for 3 glasses of wine(after 2 days of decorating I thought When a voice said are we going for a pint? I would be treated for all the paint fumes I had to inhale No such Luck ). Oh and the Beer was 25p Off £1.85 a pint in spoons last night. So all in all a good day
Of course Thank you to MY supervisor and Apprentice Jan. Who held the torch and remembered where I had placed the spindle for safe keeping, Otherwise I would have replaced the switch.