Fridge 12v supply on the move (1 Viewer)

[Mr Colpot]

I have taken the Fridge out ready for the new one to be fitted. I have a temp Coolbox (mains/12v/gas) in place until I can get the new fridge fitted when we come back from hols in August.

I have the mains in place and working but have 2 feeds for 12v - one is live when the engine is not running, but goes off when the engine is started. The other is a thicker pair of cables which I guess from the wiring diagram goes to the leisure battery (or does it?)
Whether I start the Engine or not there is not voltage on these cables.

I assume the switching is done on the Fridge PCB normally so that when the 12v on the small cable goes off it allows the thicker cable to supply the feed but I am only guessing.

Anyone have any ideas what should be happening on the 12v Supply.
(As temp measure am going to run the 12v mode from the socket in the cab which is rated 190w and the Coolbox is 90w but need to know info for when new Fridge is fitted in August)

 

[DBK]

The fridge should be run from a supply which only works when the engine is running, if you want to avoid flat batteries.

 

[jockaneezer]

Not entirely sure about this but I wouldn't connect straight to your leisure battery or 12 volt socket in the cab as a cool box will soon flatten the leisure or cab battery. I think you need to find a 12 volt feed which is live only when the engine's running.

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[Mr Colpot]

Thanks - the socket in the cab is only live when the engine is running.

 

[DBK]

You may have to run wires from the dashboard socket but if there was a fridge there before the wiring should already be in place.

On our Dometic 3 way fridge we have to manually switch between 12, 240v or gas. The switching is not automatic.

 

[Mr Colpot]

You may have to run wires from the dashboard socket but if there was a fridge there before the wiring should already be in place.

On our Dometic 3 way fridge we have to manually switch between 12, 240v or gas. The switching is not automatic.

Thanks, the cab socket is only a temporary measure while we are away next week for 2 weeks. The wiring is there for the Fridge when the replacement is fitted in August but the cable for the 12v is too big for me to fit a temp 12v socket on and I am running out of time before we are in the tunnel on satuday

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[Wildman]

the fridge relay is usually powered on by the alternator so the engine must be running, not just the ignition switched on.

 

[Mr Colpot]

Well it looks like I have sorted it (with the help of the AA (roadside not alcohol!)
Went to start the van as I wanted to test the 12v feed and it wouldnt start - just turned over.
Thought I must have blown a fuse so tested all the obvious (to me!) ones like fuel pump and starter.
In the end I called Saga (AA) Motorhome Assistance and the very nice Guy turned up within half an hour and set about checking everything I had and then he attached the diagnostics but it wouldnt talk to the Motorhome, so he set about checking some more fuses and he found the Engine Management fuse was blown (he said it has been replaced before).
Now the Van started first turn and I now have 12v feed to the coolbox from the original fridge feed so I dont need to connect to the cab socket, Its a bit of a roller coaster this new to us perfect layout motorhome.
Thanks again for the advice and comments.