power converter role

Hi I have just purchased a 2003 colonial van made by Imperial Vans.
Under the fridge is a power converter reducing power from 240v to 12v. I can not find out what it services as with battery connected or disconnected and 240 on in has no effect on anything.
can anyone advise? I contacted Imperial but they were very vague.
also has anyone had to fit a picnic table into the side wall of van what are the issues to look for .I don't want to cut wall out to find major to re build.


thanks Frank Tassie