Thetford n3141. Fridge 12 volt wiring.

[Darcar]

We’ve got a “ thetford N3141” fridge fitted in our van, and I must say it’s a great unit, works very well on both gas and 240volt.

However I’v never be able to get it to run on the 12volt supply! It has a 12v multi plug out of the back with 5 wires in. The two low volt wires, to run the control panel and internal lights. The two heavy high volt wires are too power it when switched to 12volt, then there’s a orange wire which is a” switching wire “ and is soposed to go to the engine battery ( I think ) to tell the fridge so choose the 12volt option.

My problem is our van runs 24volt engine batteries, so I can’t simply connect it to them.
It also doesn’t work when I connect it to the 12volt leisure batteries, the fridge won’t go into the 12volt mode.

I find the black art of electric very hard to understand. So can anyone tell me where to shove the orange wire to get it to switch to 12volt?

Thanks Darren.

 

[Deleted member 4404]

I've uploaded an installation manual to resources. HERE It you look at chapter 6, table 4 about DC connection, there is an option if the D+ signal is not available, this should then run off your 12v leisure batteries. The 12v option is usually used to maintain the temp while driving, so I don't know how efficient it would be.

 

[Darcar]

I've uploaded an installation manual to resources. HERE It you look at chapter 6, table 4 about DC connection, there is an option if the D+ signal is not available, this should then run off your 12v leisure batteries. The 12v option is usually used to maintain the temp while driving, so I don't know how efficient it would be.

Thanks for that Edina, I’v looked at the installation booklet.

Obviously i would only want it to be switched to 12volt while driving. So if I put a switch in the bridge wire between the low volt + and D+ wire, would this switch then turn it onto the 12volt supply?
Thanks again Darren.

 

[Deleted member 4404]

Thanks for that Edina, I’v looked at the installation booklet.

Obviously i would only want it to be switched to 12volt while driving. So if I put a switch in the bridge wire between the low volt + and D+ wire, would this switch then turn it onto the 12volt supply?
Thanks again Darren.

That's the way I read it, but you may have to also select 12v from the control panel? It is not a compressor fridge, so would be a drain on the LBs (which wouldn't matter if you are driving with good charging system)

 

[Darcar]

That's the way I read it, but you may have to also select 12v from the control panel? It is not a compressor fridge, so would be a drain on the LBs (which wouldn't matter if you are driving with good charging system)

Yeah I’ll give that a try,
It will drain the leisure batteries, but they do charge from the engine batteries while driving, as I’v got a battery to battery charger/dropper, ( from 24v to12volt )
My only concern is that, we forget to switch back to gas or 240volt when we stop! Although the fridge does this automatically now between 240volt and Lpg.

I’ll let you know when I do it.
Thanks

 

[Millie Master]

I've uploaded an installation manual to resources. HERE It you look at chapter 6, table 4 about DC connection, there is an option if the D+ signal is not available, this should then run off your 12v leisure batteries. The 12v option is usually used to maintain the temp while driving, so I don't know how efficient it would be.

Ain't our Edina a little star looking after us in the way he does.....