Is it a Devon? If so there should be a relay underneath which allows the fridge to run on 12V when travelling.
Looks like a piece of standard Devon bodgery . There is something underneath, which I'd always taking to be an electronic split charge jobbie. Didn't look too closely, tho'
Through the bulkhead to where the fridge is but from there I don't know I am presuming it has something to do with the fridge