# Dometic fridge not working 12v



## jonasw19 (Jun 11, 2010)

Dometic RM7291L
Fridge works fine on gas
Used to also work on gas whilst engine was running
Also used to work on 12v only when engine running

Now when engine is started step retracts ok
Fridge goes off if gas is selected, light goes out inside.

If 12v is selected, step still retracts the 12v green led lights for a few seconds but then goes off.

No cooling on a long drive (12v selected)

Anyone any ideas
Also has anyone replaced a 12v heating element on this sort of fridge, how easy is it?

Thanks in advance

Jon


----------



## listerdiesel (Aug 3, 2012)

If you mean the 12V fridge Indicator goes out after a while, it sounds as though you have a bad connection on the 12V side that is initially sufficient to start the fridge up, but then overheats and breaks contact.

As it is a high-current feed (8-10 Amps) any poor connection will rapidly overheat and burn, so I'd check back through the wiring and see if you have anything that looks a bit 'toasty'.

Peter


----------



## jonasw19 (Jun 11, 2010)

Thanks Peter

I have tried to look through the rats nest of wiring but nothing obvious stands out. I have tried to break and remake any connectors I can see.

I do wish that the manufacturers bothered to do the wiring rather more neatly, rather than just shovelling it in every which way.

jon


----------



## Easyriders (May 16, 2011)

We had a similar problem, turned out to be a loose wire causing a short.
Like you, we couldn't make much sense of the wiring, and the wiring diagram in the handbook was no real help. We are both pretty competent with domestic wiring, but MH wiring is something else!

We took it to an auto electrician we know locally, he fixed it very quickly and didn't even charge us, as we are old customers of his. We did give him £20 as a thank you, though.


----------



## jonasw19 (Jun 11, 2010)

*Further update*

Took out the fridge unit today and tried a bit more fault finding, with agrown up who does electronics.

Gas and 240v sides work fine
The 12v heater element seems ok in that we by passed all the controls and fed it 12v and it sat there merrily consuming 10amps, so that bit is good.

Next looked at the control board for the fridge and determined that there seemed to be no 12 volt signal when the engine was started, hence the fridge control relay could not switch the 12v high current supply on.

Question is where does this signal for the fridge come from, the electric step which is retracted when the engine starts up, is fine and retracts automatically when it should, and is isolated when the engine is runnig.

The Sargent box is showing no fault codes but the display suggests that the engine battery is critically low. It definitely isn't as it has been tested under load and is good.

What controls the link between the alternator / engine battery and the hab side of things?

Jon


----------



## kenny (Jun 4, 2005)

*fridge elc*

Hi i am having same trouble has you,bur i am in luck has a friend is a retired board man so am waiting fer winter months to get it fixed, with regard where does the board know what to do the switch on the fridge goes to the board then the alternator puts a higher voltage in the the circuit telling it to switch on the fault is between the fuse and god knows what in between ,but the fridge works good on gas when traveling if you look in forums you will see plenty of write ups about this , mine will be on gas from home next week till we get to lamanger Kenny


----------



## Andythebuilder (Apr 29, 2012)

Hi all just seen your post, we had a similar problem when in spain last winter, it turned out to be a 3 amp fuse under the bonnet next to the battery,in a holder fixed to the bulkhead. I traced it back by following the wires back from the fridge relay using a continuity tester. This wire is the "signal" for the relay to switch over from start up and eventually i traced it back to the charge circuit from the relay. Our van is a fiat ducato mk2 2001.
I hope this helps you both
Cheers andythebuilder.


----------

