As far as I know, the fridge circuit can use gas, 12V jheater or a 230V heater.
the 2 electric heaters are separate so your 230 V one may have failes - but check switches and wiring as well.
You use to be able to get a 240/12v element for those refrig's. Try someone who repairs Caravan refrig's.
12v use is only for travelling and used after you get it cold on gas or 240v
XXX, February 2016