It'll work off the car because it's working on 12volts
Gas you say is fine.
I had the same prob: and thought it was wired in to the 10amp circuit along with sockets like my last caravan but found it was plugged in to a socket in the cupboard next to fridge [just got the c/van] and found the fuse in the plug had blown. So check other 13 amp sockets you have,if any, the mcb fuse box make sure none have tripped, can't say about the fridge it'self.
nobby, August 2008