Fridge problem (1 Viewer)

Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
I've a Dometic 3 way fridge RM6401L and it's been working well on all three power sources until this week when it's stopped cooling on gas.
12 and 230 volts are fine.
The fridge lights on gas and stays lit and the fridge fans come on periodically as I'd expect, so somethings getting hot, but no cooling.

The only thing I can think of is some debris has fallen down the flue, but no idea if that would cause these symptoms ?
Unfortunately the lower vent is mounted in the floor and inaccessible behind the bumper. So I can't get to it to clean without taking the fridge out.
I'm on the road in Italy heading for south France and so not really possible.

I'd read an excellent write up on here by I think autorouter ? explaining how the fridge works on all sources, I thought I'd bookmarked it for future reference, but can I find it ? no.

Anyone have any ideas for a simple fix :rolleyes:

TIA
 
Sep 3, 2012
7,637
26,266
Cheshire
Funster No
22,759
MH
C Class Elddis 175
Exp
8+ years
Can you get a vacuum cleaner hose ,or a thinner tube attached down by the burner to suck out any debris ?
 
OP
OP
Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
Can you get a vacuum cleaner hose ,or a thinner tube attached down by the burner to suck out any debris ?
Tried that and it made no difference
Tricky to do as there is some kind of baffle in the flue so I don't know how effective that would ever be.
I believe when debris gathers or falls it usually stops the fridge lighting ?
Mine lights and stays lit 🤷‍♂️

It's cramping my FLT credentials at the moment :rofl:
 
May 17, 2016
3,646
7,890
Aberdeenshire
Funster No
43,137
MH
B524
Exp
2nd base
Tricky if you can't get in to the bottom vent but does sound the same as my problem....


Certainly sounds like the flue needs cleaned out.
 
OP
OP
Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
Tricky if you can't get in to the bottom vent but does sound the same as my problem....


Certainly sounds like the flue needs cleaned out.
Yes it does (y)

No access to the lower vent is a real pita

It'll have to wait until I'm home and can get the fridge out

Thanks

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Dec 17, 2016
978
1,004
Malvern
Funster No
46,488
MH
Hymer B525 2006 A cl
Exp
2012
In mine the baffle is suspended in the flue on a thin wire that attaches to the top of the flue.You should be able to unclip it an lift it out in order to pass a thin tube down attached to the end of the vacuum hose
 
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Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
Ok, so back home now and investigation underway into why fridge stopped working on gas.
I've taken fridge out, no debris apparent at gas jet, baffle removed and bottle brush pushed down the flue. Some debris fell out but not that much really.
All vacuumed up and general clean up of back of fridge.

Is there anything else I need to check whilst it's out ?

I could replace the gas jet I suppose but it was lighting ok, just wouldn't cool.
From what I can see, all 3 sources use the same refridgerant / gas circuit which goes behind the aluminum cowl encasing the flue, I assume this is where it heats the refridgerant gas in the pipework.
If anyone can confirm this that would be helpful as it would exclude a problem with the refridgerant.
Unfortunately I can't reconnect and test it while it's out and have no lower vent to check things through.
TIA
 

68c

Oct 22, 2019
1,840
2,848
Southampton
Funster No
65,959
MH
2001 Pilote 270
Exp
Since 2004
Yes, there are the three heat sources inside that tube, any of which will make the fridge cool. Can you see if the gas flame is actualy alight? If not could be an ignition fault, test by holding one of those gas lighters at the bottom of thr exhaust tube. If it does not light then there is no gas flow. There is a small filter before the gas jet, a sort of sintered metal affair, that gums ups particularly in cold weather. Clean in a solvent, lighter fluid etc.
 
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OP
Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
Thanks, I'll check that filter tomorrow.
Unfortunately it's impossible to see the flame when the fridge is installed with no lower vent or inspection window inside the fridge as some models have.
I assume it lit as the flashing igniter light went out.
I might see if I can rig up a temporary gas supply with plastic tube
 
Jul 6, 2009
1,842
2,294
Funster No
7,383
Have you check that the regulator is providing enough gas. A lot of Truma reg have failed due to contamination

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68c

Oct 22, 2019
1,840
2,848
Southampton
Funster No
65,959
MH
2001 Pilote 270
Exp
Since 2004
Thanks, I'll check that filter tomorrow.
Unfortunately it's impossible to see the flame when the fridge is installed with no lower vent or inspection window inside the fridge as some models have.
I assume it lit as the flashing igniter light went out.
I might see if I can rig up a temporary gas supply with plastic

Assuming both the 12v and 240v heaters are cold, feel if any heat comes from the exhaust when trying on gas, it will not be very hot but should be noticeable.
One fault I had after a rather bumpy ride was the gas had lit up OK and felt warm at the exhaust but little cooling. Turned out the jolting had dislodged the baffle inside the exhaust tube, the baffle is about three inches long and hangs loose on a wire inside the exhaust tube. It is twisted to encourage the heat from the flame to spiral (helix?) and stay in contact with the exhaust tube inner surface and so heat the cooling chemicals. For info the gas exhaust pipe is the inner tube, about one inch in diameter. This wrapped in something like fibreglass wool which is then covered with the shiny three inch sleeve. The chemical tube runs up inside this insulated tube in contact with the heated exhaust tube. The two electric elements are long rods with wires attached also inside the insulation and in contact with the chemical tube. You are correct in assuming there is no major problem with the fluid side of things if it cools on electric.
 
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Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
Assuming both the 12v and 240v heaters are cold, feel if any heat comes from the exhaust when trying on gas, it will not be very hot but should be noticeable.
One fault I had after a rather bumpy ride was the gas had lit up OK and felt warm at the exhaust but little cooling. Turned out the jolting had dislodged the baffle inside the exhaust tube, the baffle is about three inches long and hangs loose on a wire inside the exhaust tube. It is twisted to encourage the heat from the flame to spiral (helix?) and stay in contact with the exhaust tube inner surface and so heat the cooling chemicals. For info the gas exhaust pipe is the inner tube, about one inch in diameter. This wrapped in something like fibreglass wool which is then covered with the shiny three inch sleeve. The chemical tube runs up inside this insulated tube in contact with the heated exhaust tube. The two electric elements are long rods with wires attached also inside the insulation and in contact with the chemical tube. You are correct in assuming there is no major problem with the fluid side of things if it cools on electric.
The baffle looked to be copper but the wire is steel and badly corroded. I'll strip a length of twin & earth I think for the copper wire and make a replacement.
 
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Apr 27, 2008
11,862
14,121
Eastbourne East Sussex
Funster No
2,327
MH
Hymer low profile
Exp
Since 1972
Is the gas jet operating at full blast. Sometimes a partial blockage may let it light but not produce enough heat. Should be an audible roaring sound though you may have trouble hearing it as your bottom vent is inaccessible.
 
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Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
How 'large' should the flame be ?
I can't say I've ever heard it roaring but as you say with no lower vent it's perhaps not suprising
I'll see if I can rig up a temporary gas supply tomorrow without electrics connected and see what the flame is like

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68c

Oct 22, 2019
1,840
2,848
Southampton
Funster No
65,959
MH
2001 Pilote 270
Exp
Since 2004
I have never heard the flame roar. The flame should be blue and about 3/4" long. Of course in you installation you cannot see it. I do not remèmber the exhaust baffle being copper. I suppose a length of copper wire to hang it would be OK to test but would probably get the real part in the due course of time.
 
Jul 6, 2009
1,842
2,294
Funster No
7,383
I did wonder if my regulator is letting too much gas in I have posted a separate post so not to hijack this one!
 
Oct 29, 2008
5,112
6,101
West Yorkshire
Funster No
4,712
MH
PVC
Exp
since 2008
Is the gas jet operating at full blast. Sometimes a partial blockage may let it light but not produce enough heat. Should be an audible roaring sound though you may have trouble hearing it as your bottom vent is inaccessible.
This is what mine was like, burning but not roaring until I cleaned the jet

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denisejoe

LIFE MEMBER
Aug 6, 2014
5,666
12,243
Warden isle of sheppy
Funster No
32,702
MH
A Class
Exp
Since 2004
The easiest way to check if gas is lit is to feel on the right side of the top vent to see if you can feel any warmth.
ps saw a German with the same van as you and he had installed a what looked cassette door where the gas burner goes.
 
OP
OP
Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
An update : Gas jet assembly removed and flue cleaned out. Neither were particularly dirty.
I blew some compressed air and vacced the gas jet aware not to poke anything in it.
Reassembled and all working nicely.
I can only assume it was lighting but the flame was restricted by debris preventing any cooling effect.
I also took the opportunity to extend the electrical cables to make removal easier in the future. Previously I had to lift the gas hob in order to disconnect them, and skin my knuckles in the process.
I couldn't find a filter to clean on the gas line though.
Hopefully it won't need any more attention for a while
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,447
50,414
Dark side of the moon
Funster No
172
Exp
Since 2005
If it's lit you should feel heat at the top vent, the flue is usually to one end of the vent grid.
Run your hand along the vent feeling for warm air.
It could also be the conductive paste behind the inner cooling fins. Unlikely if it's working properly on other sources though.
 
OP
OP
Figaro
Feb 22, 2011
9,988
20,644
Newcastle under Lyme
Funster No
15,397
MH
Hymer B544 A Class
Exp
Since 2015
If it's lit you should feel heat at the top vent, the flue is usually to one end of the vent grid.
Run your hand along the vent feeling for warm air.
It could also be the conductive paste behind the inner cooling fins. Unlikely if it's working properly on other sources though.

When it was running on gas but not cooling, it did seem to be warm at the vent, but as said, no cooling 🤷‍♂️
All seems to be working ok now though, so not sure what the problem was, I can only assume lit but not fully for some reason.
I replaced the thermal paste a couple of years ago and found a big improvement

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JJ

Mágica
May 1, 2008
19,288
48,380
Quinta Majay, Pinheiro Bordalo, Portugal
Funster No
2,459
MH
Burstner Privilege T
Exp
over 50 years
I had the exact same problem which was fixed yesterday by fitting a new burner/jet and a new gas control valve.

(Completely stripping down and cleaning the burner and flue hadn't helped.)

I am now also free to go "off site" motorhoming once again... yipppppy!

JJ :cool:
 

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