Hymer motorhome Thetford fridge N3142 not working on 12v.

Last time we were out in our Hymer I noticed that when the engine was running the Thetford fridge freezer was not running off the 12 volts from the engine. The fridge freezer can work off gas, mains electricity or 12 volts; it will only work from 12 volts when the engine is running because the fridge uses a lot of power. Changeover between the 3 power sources is automatic, the Thetford fridge selects the mains first, if mains is not available it uses gas or 12 volts.

At the moment, November, it’s not a huge problem that the fridge will not work off 12 volts, there is obviously nothing wrong with the fridge cooling because it works off mains or gas, it’s only the 12 volt that is not working. 

A quick search on the internet revealed that this is a fairly common problem which means there are a lot of forum posts from people whose motorhome fridges don ‘t work on 12 volts. I spent a LONG time trawling through long threads of conversations and reading them carefully to understand what might be the cause of the problem.

The number one cause of most people’s motorhome fridge not working on 12 volts was a fuse on the main fuse panel, I went and checked all the fuses but didn’t find any fault. Back to the internet and a LOT more reading.