Trip so far has been spot on

Only thing is that my fridge does not seem to be working on hookup?
Works fine on gas but when I try the switch in the 240v position the fridge gets warmer.
I haven't left it that long before reverting to gas but wondered if any of you wise folk know how to make it work on hookup?
All I have is a switch and a temperature dial.
I have made sure the the socket the fridge plugs into works and I don't have a zig or any thing fancy.
The van is a really early German wasty
.
Cheers guys