In an Engel, the thermostat bulb, which I guess you are talking about, sits on the back wall of the fridge under a screw on cover ( 1 screw in my 2000), and passes through a screwed on cover which also covers the entry of the cooling pipes.
Both the thermostat and the whole cooling unit can be changed by undoing 3 or 4 screws, as well as the outer shell which is held by 8 or so screws.
Regard sPhilip A

