From the description of the fault the problem is with the unit (the pipe work at the back has a ammonia leak) and needs replacing, if this is a oldish fridge it is unlikely you will not be able to get one as they do not make them anymore, your best bet is to buy a second hand one but insist on seeing it working before you buy. no point in trying it on battery as it draws 7amp and will flatten the battery in no time.
Electrolux engineer (ret)
Electrolux engineer (Retired), July 2008