Dometic fridge 12v not working (1 Viewer)

[Semore]

Hi everyone, apologies for the question, but... We have recently bought a 2004 fiat ducato 2.0L Carioca 656 motorhome.

It came with a few issues which I am working through, however I am lost with the fridge on 12v issue. After reading through the forums, I understand that it will only work on 12v if the engine is running, however, with it running I don't get a light on the fridge. I understand it could be a fuse issue, there are 4 fuse boxes and a C16 MCB on the van, so not sure where exactly to look. The photos show the fuse box behind the drivers seat, the fridge and the MCB under the stove (next to the fridge), there are 2 fuse boxes in front of the passenger and driver, then 1 in the engine bay. I have checked these and found no blown fuses (as far as I can tell). The leisure battery is under the passenger seat (we bought a new one) and I think there is an inverter under the drivers seat. Can anyone help please?

Thanks in advance

 

[Jimbohorlicks]

Does the fridge get cold when the engine is running?
Is there a light on when it's on hook up or on gas?
It may be best to actually remove the fuses and clean the contact and reinsert. Just to make sure its not that.
Looking at the pictures you put up it looks as though the fridge is switched off anyway. So you won't get a light. Turn the switch away from the O position.

 

[GeoffnDee]

Apart from the 20amp fridge fuse shown in what are the habitation fuses shown in the photo there may also be a separate relay/fuse for the fridge supply along with maybe another , for split charging , under the bonnet , near the starter battery ,
The MCB would only be involved for 230v operation and I would expect the other fuse boxes to be linked to the Fiat side of the electrics , not the habitation side , with their uses being shown in a Fiat Ducato van (X244) handbook or fuse box diagram.

 

[Spriddler]

In your first photo the yellow 20 amp fridge fuse doesn't look to be fully inserted.

 

[jockaneezer]

The fridge works from 12 volts via a small electric heater (about the size and shape of an old cigar tube, with two supply wires coming out of it, there's also a 240 volt one too for running off mains electric) it's not unknown for these to fail (more likely a possibility with a 2004 model)
They're located inside the flue at the back of the fridge, usually hidden inside a tin wrapper and some fibreglass insulation, but you can generally get to their terminations by removing your lower fridge vent.
Get yourself a multimeter and check to see if there is 12 volts at their terminal block and then check if the heaters themselves are viable. An open circuit or extremely high resistance will generally mean it's kaput, replacements cost between £50 and £100 depending on the model.

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[peterc10]

Looking at the icons on your first picture I would guess the yellow 20A fuse is for the 12v fridge. It should only work when the engine is running otherwise it will flatten the battery in no time. The third photo is irrelevant as it shows the 240 mains breakers.

 

[pappajohn]

Either change the 20a fuse or check it with a meter.
These fuses can blow right at the end where you cant see the wire.

 

[Semore]

hi thankyou all for your replies, I will check out what you have mentioned and see where we go! just a few questions... The starter battery, is that the main battery? is there a photo of it? the 20amp fuse has been in and out a few times to no avail, the lights work on gas and electric (I had to 'manipulate' the gas valve as shown in the forums) but not on 12whem engine started up.

 

[GeoffnDee]

The starter battery is normally the one under the bonnet on the drivers side ( on a X244 Ducato) and could be described as the main battery, the leisure battery should be the supply for the fridge electronics, which seems to be ok , with the starter battery being used to supply the 12v heater element supply

 

[Clivefog]

My fridge has a 2 amp fuse by the leisure battery this supplies 12v to the fridge panel directly without going through the onboard 12v system.

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[Vikdikdok]

Don't trust visually looking at the fuses - check continuity with multimeter

 

[ManTheVan]

There is also a signal wire to the fridge (called D+) which tells it when the ignition is on. It will then usually switch automatically to 12V. If all the fridge lights go out when the ignition is on, then it might indicate that there’s a fault with the main circuit board, but eliminate the other causes by testing the voltage at the 12V element and fuses as others have suggested.

If there is no voltage at the element, then it is worth changing the multimeter to resistance mode (a little Greek omega sign like a horseshoe) and seeing if there is continuity (an unbroken circuit) in the 12V heater element.

If there is, then there might be a fault in the main circuit board. If you can get this out (and it’s a pain in the arse to do so) then look up QER electronic repairs on Google and send it there for a diagnosis and repair.

It’s also worth joining as a full member as there’s lots more advice and knowledge to be had.

Good luck.

 

[Semore]

Hi, I have taken both seats out and what I thought might be an inverter is actually the battery charger (see photo). There doesn't appear to be any inline fuses, other than the ones shown in the black cases on the leisure battery and charger (are these what you mean?). I could not find any fuses in the engine bay near the battery or under the scuttle (unless the photos show them?). I have ordered a multimeter to try and test what I can. Is there any other advice or something that can be seen from the photos?

 

[Semore]

Hi, looking at the fridge heating element (I think), it doesn't appear to go into the flue. It comes up through the fins and then to the top of the fridge inside. Is this normal?

 

[Jabstatt]

Note that the D+ signal is only present when there is alternator output. Not just ignition on.

Tony

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[GeoffnDee]

They are the elements (12v + 230v) and they should both be along side the gas burner heat outlet chimney within an insulated metal cover.
If it helps I think your fridge is a Dometic RM7xx1 MES series item and www.leisurespares.co.uk show the parts diagram for them.
If it is a RM7xx1 model there should be a 12v permanent supply from the leisure battery (black + violet cables) on a block connector at the rear of the fridge for the control operation . there should also be white and red cables at the block connector which are for the 12v heating element supply and there should be 12v power from the starter battery at these connections when the engine is running , this supply is through a relay that is operated from a D+ alternator running signal .

 

[Semore]

Hi, after closer inspection, they are indeed the 230 and 12v elements. Not sure where both ends lead, but the do disappear above the fridge internally and inbetween the fins at the back of the fridge. Not sure where they connect to the flue (or even if they do), as I cannot see anything from the lower access door.
The wires, as you can see from the photos are like you say in block connectors, visible in the lower access door. I have ordered a multimeter that hopefully will arrive tomorrow. Do you know the way to test them to check if they are ok?

 

[ManTheVan]

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[GeoffnDee]

The cables on the right of the block connector appear to be the fridge mains supply so make sure that mains power is disconnected from the Motorhome if you are going to be working in that area .
There should be permanent positive 12v supply at the violet cable ,for the fridge electronics/controls to operate and a separate 12v positive supply ,for the 12v heater element , at the red cable , but this supply will only be there when the engine is running .
The two black and white cables are the negative sides.

 

[DavidG58]

I wouldn’t worry about the 12V not working on the fridge , at best it will maintain temperature over a long journey, as long as it is cold before you set off, then don’t open door too much it will be fine for a few hours travelling