12v electrical connection to electrolux fridge in camper ?

I am renovating a camper van. The van came with an Electrolux fridge connected to the gas bottle but with a tangle of disconnected wiring at the back.
Model number 114A2/
there is a terminal block with 2 black wires leading from it.
I assume there's no preference for which is live and which is Earth.
Any ideas before I ignite the neighbourhood?

Wullie. Irvine
April 2009