Dometic Caravan 3way Fridge Fault

Submitted: Tuesday, Oct 22, 2013 at 19:40
ThreadID: 104828 Views:10310 Replies:4 FollowUps:8
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Hi All
Have a problem with my 3way Fridge,will not work off 12v from my van power supply and will not work when connected to the car when towing. Has been working previously with no problems. All other 12v working fine. Just wondering if the fridge has a Fuse in the Fridge as there is no Fuse in the Fuse box. Has anyone else had a similar problem. Van is only 2 Years Old. Any help greatly appreciated before I call out the Fridge Doctor.
Cheers Steve
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Reply By: lancie49 - Tuesday, Oct 22, 2013 at 20:10

Tuesday, Oct 22, 2013 at 20:10
My guess would be a blown 12v element.
Lots of reports and history on these elements on CF.
They seem to be a very common problem that Dometic are aware of.
AnswerID: 520219

Follow Up By: Member - LeighW - Wednesday, Oct 23, 2013 at 12:04

Wednesday, Oct 23, 2013 at 12:04
Most likely element though if a AES model may not be.

Also worth checking to see if a movement activated switch is fitted as it maybe faulty.

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Reply By: oldtrack123 - Wednesday, Oct 23, 2013 at 12:20

Wednesday, Oct 23, 2013 at 12:20
Hi
No fuse in the fridge itself, although there MAY be one in the supply feed.
Are you saying the fridge element is not getting hot [check the bioler outlet @ the top for heat ]
or just that the fridge is not cooling on 12V??
Model # of fridge is required to give any detailed suggestions[like oils ,ALL fridges are not the same]
The 12V elements unlike the 240V elements have a low failure rate, IMHO.

PeterQ
AnswerID: 520242

Follow Up By: Stephen H - Wednesday, Oct 23, 2013 at 12:45

Wednesday, Oct 23, 2013 at 12:45
Hi,
Sorry should have included Model#,It's a Dometic 175lt 3way Absorption Fridge RM7851. The Fridge is not cooling when running on 12v or connected to the tow vehicle. Works fine on Gas and 240vt.
Cheers Steve
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Follow Up By: oldtrack123 - Wednesday, Oct 23, 2013 at 15:31

Wednesday, Oct 23, 2013 at 15:31
Hi
That makes it a MES [manual energy select] model
The first thing to do is check that you have 12V AT the fridge terminals when it should be running
Then we can take it from there.

PeterQ
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FollowupID: 800667

Follow Up By: Stephen H - Wednesday, Oct 23, 2013 at 19:46

Wednesday, Oct 23, 2013 at 19:46
Hi Peter,
First of all thank you very much for your help. I checked the power supply at the Fridge. It has two 12v connections One is a12vDC Heating Element the other is 12vDC Electronic.There is no Power at either connection. Both lots of wires come out of a 12v 30amp Relay that has a built in Fuse. Checked Fuse OK. Fridge was in running mode when Checked.
Cheers Steve
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FollowupID: 800685

Follow Up By: oldtrack123 - Thursday, Oct 24, 2013 at 00:37

Thursday, Oct 24, 2013 at 00:37
HI Steve
Yours being a MES [manual energy source ]selection the electronic 12V is for the gas ignitor /reignitor
That should be from the van battery with small dia cables but fused[5A] as close as possible to the van battery/

THe heating element should not be connected to the van battery but supplied by it's own seperate heavy cables from the vehicle battery
fused again at the vehicle battery[20A]
that feed should also have some automatic means of disconnecting the fridge from the vehicle battery when the engine is not running.
That last can be done by :
[a] an ignition conrtolled realy in the vehicle
[b] a"Fridge Switch in the van which is actually a motion sensor Which detects when the van is not in motion & then after a short time delay switches off
[[c]a voltage sensitive realy which detects the voltage available & will only connect the fridge when the voltage is over 12.7V approx.

To complicate matters many van makers DO NOT wire correctly & have both feeds connected to the van battery
i
THat will lead to the van battery never being fully charged while driving'
You would need to trace back the wiring of BOTH circuits & see when you can pick up 12V
note TESTING with a digital volt meter can be misleading
They will detect voltages that cannot support any real current flow
Best done with a 12V test lamp & judge voltage by brightness, a stop light bulb is a good size

PeterQ
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FollowupID: 800695

Follow Up By: Nomadic Navara - Friday, Oct 25, 2013 at 00:56

Friday, Oct 25, 2013 at 00:56
I have just downloaded the manual for the RM7851. It shows three separate 12 V inputs. There is the heavy cable from the tug. There is a second light duty one from the vans house battery and the third one is the D+ wire. Quote from the handbook:

I have not copied the solar instructions (S+)

From your description of power coming from a relay it looks like the fridge was not wired correctly.
PeterD
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Follow Up By: Stephen H - Friday, Oct 25, 2013 at 08:52

Friday, Oct 25, 2013 at 08:52
Hi All,
Thanks everyone for your help. I have done everything that you have suggested and still not working. I know I'm out of my league with this one,time to call the fridge Doctor and Pay up. Thanks again all and safe travels.
Cheers Steve
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FollowupID: 800755

Follow Up By: oldtrack123 - Saturday, Oct 26, 2013 at 00:25

Saturday, Oct 26, 2013 at 00:25
Hi PeterD
Those multi model manuals are confusing sometimes
I think if you recheck you will find the 7851 is a MES not an AES model

BUT it does have electronic ignition from the house battery

PeterQ
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FollowupID: 800794

Reply By: landseka - Wednesday, Oct 23, 2013 at 20:08

Wednesday, Oct 23, 2013 at 20:08
IMO the fridge should not work from the van 12v power supply. The power should be drawn from a supply direct from your car battery/alternator through heavy duty cables via an Andersen Plug joining the van to the car.

Again IMO this supply ONLY runs the fridge.

You need to check where your fridge draws it's power from & check that a fuse is not blown in the car. Is there power to the car trailer plug/Andersen Plug. It sounds like you have no 12v power to the fridge.

In my own case the method I describe is how mine is set up. My van 'house' battery only gets charge from solar or the onboard charger when hooked to shore power & there is insufficient solar input.

Cheers Neil
AnswerID: 520262

Reply By: Povertypete - Friday, Oct 25, 2013 at 10:16

Friday, Oct 25, 2013 at 10:16
Hi Steve I know I'm late but I had the same problem and NOBODY could solve the problem. Replaced / upgraded wiring to and from the battery and got opinions over 10000ks of travel and bloody frustrated. I got sick of the experts and started checking myself despite my lack of electronic/refrigeration technology and finally found the fault to be the selector switch on the front of the fridge. Check the voltage to and from that switch via the rear access panel. the fridge had to be removed to replace the switch but everything is good now Good luck Peter
AnswerID: 520327

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