# Dometic fridge not working on gas



## sheds (Nov 6, 2005)

Hi, we just got back from a three month trip and managed to keep food fresh by hooking up to campsite electricity because our dometic RM7655 fridge won't work on gas. I followed the basic steps of diagnosis by googling and I found that the gas jet is clean, the igniter clicks away happily without igniting any gas, and that if I apply a flame to the burner while the igniter is clicking, not gas flame appears. So I assume no gas is getting to the burner. I checked the 3 electrical connections to the gas valve/solenoid unit and replaced any which looked corroded, but still no gas is flowing. Of course I could test that the control unit is applying a current to the gas valve (if I knew how to do this with my basic gunson electro tester). A replacement gas valve unit is pricey at £155 so I was wondering if anyone can help me with the last step of diagnosis (is current flowing when unit is switched to Gas?) and whether the gas valve is a part I can change given that it involves gas and hence safety. 

If not next step is to find a local firm who do dometic fridge maintenance in the Reading area if anyone can advise?

Can anyone give me the basic steps to test the current flow to this device?

thanks

Ian


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## raynipper (Aug 4, 2008)

Temperamental aren't they. If you can easily access the gas valve try giving it a right whack. You have nothing to lose as all these valves can stick.

Ray.


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## Webby1 (Mar 11, 2012)

raynipper said:


> Temperamental aren't they. If you can easily access the gas valve try giving it a right whack. You have nothing to lose as all these valves can stick.
> 
> Ray.


After doing all the cleaning it would spark but still not light.

The whack on the gas valve/solenoid freed up something and all is now working well.


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## sheds (Nov 6, 2005)

As you say, nothing to lose! I did think of this yesterday as it has a solenoid mechanism inside but I was too hot in the sun so will give that a try today as it is cooler here now. I shall also read the Gunson manual to figure out how to test a current flow. Trouble is it needs my partner to be in the van switching the unit on and off gas, and she gets bored doing that! I'm still hoping that we will be allowed to repeat our summer long Greek visit after Oct 31st 2019 as this has been part of our life since retirement in 2007


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## Drew (May 30, 2005)

This was posted in answer to a similar question by jhelm a few months ago.

Before attempting this isolate both 12 & 240v electric supplies and turn gas off.

Might I suggest that you completely dismantle the gas burner assembly and clear out the debris (Rust) from the burner itself. I will guarantee that you will remove about a tea spoonful of rust. If as you say that you had difficulty in removing the retaining nut, pre soak it with a good squirt of WD40 and leave it for a while. The little jet shown will need a good clean but no attempt should be made to enlarge the hole although it can be cleaned with a Primus Pricker or an extremely fine sewing needle. If you attempt this take care not to lose or damage the jet. Before assembling clean out the flu, most of the debris comes from this.

I believe on an absorption fridge it is impossible to top up the refrigerant.

I used to do this twice a year on my 1993 Hymer that I had for nearly twenty years and never once did it let me down. If you have any questions please ask.

*Posted by Eurojohn.*

Firstly with the outer vent cover off and the burner shield removed have a helper turn the control from off to gas operation, if the igniter sparks but no flame is produced you can safely assume no gas is being delivered to the burner, the most common reason is dirt, dust, rust covering the top of burner, it is very very unlikely to be a blocked jet as there is an efficient filter / strainer upstream of jet. It is also possible that there is a fault / failure of the gas control device, however that is quite rare, so won't go into detail here.
If you consider yourself proficient enough to carry out DIY repairs you will need a pozi drive No.2 screwdriver, an 11mm open end spanner and a 13mm open end spanner.
Before you start work turn fridge control to off and isolate the gas supply to fridge.
If fitted remove the push on earth connector on burner head (later models don't have separate earth lead) then unplug the igniter and flame failure leads from the control module (they simply push in and pull out) make a note of which one goes where.
Support the square aluminium jet / burner housing with the 13mm spanner and undo the 11mm nut that retains the gas feed pipe into the burner, undo the single No.2 pozi screw that holds the burner assembly to the exhaust tube, allow the burner housing to drop away from exhaust tube and carefully remove the burner assembly, be aware that the jet is simply dropped into the housing and held in place with the feed tube, so is free to fall out and get lost on floor, it is a small pressed dished washer like device that has a tiny hole in the centre. When you have the assembly safely on a clean work surface ensure that the ring of holes at the top of the burner are clear of obstruction and clean if available blow out with compressed air, ensure the jet is actually clear but under no circumstance poke anything in it, the size of the hole is critical to the correct operation of the fridge, so long as the hole is clear and there is no damage to it you will not need a new jet they do not wear. It is possible the flue exhaust will also need cleaning, it's not unknown for them to become blocked by spiders etc. a long bottle type brush is best here , don't try to pull rag through it will get jammed, also if cleaning the flue you will need to access the top of pipe and remove the spiral baffle within the flue before you attempt to clean it, it is simply dropped back in place after cleaning.
Re-assembly is a reversal of dismantling, ensure the jet is correctly placed within the burner (dished end towards burner), at this stage do not replace the burner shield, turn on the gas supply and get your helper to turn control to gas operation, you may need to do this a few times to bleed air out of supply pipe, the burner should now light and stay alight, using a leak detector fluid ensure any joint you disturbed is sound and not leaking. Turn off fridge control and the taking care as the area will now be hot replace the shield and outer covers.

If the burner fires up but fails to stay alight the flame failure device is faulty and you will need to purchase a new burner assembly as they do not supply the flame failure probe separately.

As I mentioned earlier only attempt this if you feel confident to do so otherwise get a qualified and certified person to carry out the repairs for you.


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## eurajohn (May 9, 2005)

Are you sure it's nothing silly like the isolation tap for the fridge gas supply turned off, unusual for no gas to be present at the ignition phase.

If you contemplate the next suggestion you do it at your own peril and you will need to take all necessary precautions.
Firstly switch off the gas supply at your bottle or tank, find the union for the fridge supply and undo nut and release pipe, ensure no external ignition source in the vicinity and then get an assistant to open the supply from your bottle or tank, this should result in gas coming out of the pipe, if not you'll need to find out why.

.


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## Webby1 (Mar 11, 2012)

Drew said:


> This was posted in answer to a similar question by jhelm a few months ago.
> 
> Before attempting this isolate both 12 & 240v electric supplies and turn gas off.
> 
> ...


And THEN give it a good smack :wink2::wink2:


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## Drew (May 30, 2005)

Hi it with a hammer, with a hammer said the fitter,
Very fine men are we,
There's non so fair as can compare,
With the boys of ****.

Your as bad as Ray.


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## raynipper (Aug 4, 2008)

I used to work on the VC10 aircraft at Weybridge Surrey and often had a snag list to sort out while on nights.
On tropical trials the odd fuel transfer valve would get stuck and they would fly the aircraft back to Weybridge where a fuel fitter climbed into the 'torque' box between the wings and take out the offending valve to change for a new one.
We soon twigged that using a long lump of wood we could just open the hatch and give the 'stuck' valve a whack with the timber and voila working again.

Never heard of any further stuck valves while in service.
In fact that lump of timber was kept in the stores labeled "Fuel Valve Actuator".

Ray.


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## sheds (Nov 6, 2005)

I have checked the jet and cleaned the burner. The problem is that no gas is arriving down the pipe to the burner. I have made sure the isolator tap for the fridge is open i guess the last thing would be to check that gas is arriving at the solenoid valve, thereafter its off to drain the bank account for a new one.......


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## Mrplodd (Mar 4, 2008)

But have you tried the "Percussive remedial application tool" yet? Non technical people call them hammers!

It certainly sounds like the valve isn't doing wot it oughta so it _might_ benefit from being "persuaded" to comply with its design brief AND LET SOME BLOODY GAS THROUGH!

Andy


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## Penquin (Oct 15, 2007)

Bear in mind that the high fees the professionals charge is not for the application of said "momentum imparting device" but knowing WHERE to apply it.....

That takes years of practice and inherent knowledge to decide exactly the correct point of impact as well as a large hammer 😁


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## jhelm (Feb 9, 2008)

Did you also clean the supply pipe? It may be clogged. Disconnect it and run a wire up inside a few time back and forth. Worth a try. I just recently got mine working again following the instructions listed above.


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## LT Man (Nov 11, 2016)

Shields had same trouble this year when away Same fridge also. 

I tried the cleaning and gas valve tapping procedure etc. to no avail. 

Found it was the the wiring harness was not allowing a full 1 volt to gas valve. Was only supplying 0.7 volts which in turn did not allow valve to open .

I did the gave valve ends of the harness new fittings and cleaned up spades but still no good.
Found it to be the multi pin connector block on to the control unit not getting a good connection.. Pushed it on the side and hey presto we had lift off .I mean ignition ....

Put a bit foam on the side of it and a long cable tie around it so it was forced on to side of pins and been working fine ever since .

Hope yours is also an easy fix as these things are a bit of a nuisance.

LT Man


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## Drew (May 30, 2005)

"Found it was the the wiring harness was not allowing a full *1 volt to gas valve. Was only supplying 0.7 volts* which in turn did not allow valve to open".

I'm not quite sure if you have the correct voltage, I have never come across a gas valve that operates on only 1volt. I apologies for this post if I am wrong.


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## LT Man (Nov 11, 2016)

Drew

See page 36 of this http://web.adria.dk/wp-content/uploads/2012/05/Dometic-service-RM8XXX.pdf

Not my model as can not find it on the web but this one close enough

My local engineer told me mine was 1 volt and he must have been right as it now working after making better contacts to achieve this

LT Man


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## Drew (May 30, 2005)

Thank you LT Man, on a search I found this.

Drew

https://www.caravantalk.co.uk/commu...orrect-gas-valve-solenoid-resistance-reading/


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## raynipper (Aug 4, 2008)

I still can't see how 1 volt could actually work any physical solenoid or valve.

Ray.


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## Drew (May 30, 2005)

Like yourself Ray, I was taken by surprise.

I also can't understand why the habitation side of a motorhome is fully computerised, it is not necessary.


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## Penquin (Oct 15, 2007)

Just had the diagnosis for our fridge; the switch on the left hand side which controls EHU, 12v or gas operation, there are also the contacts to control the ignition / flame failure safety and ours has bad contacts. It needs a new unit and cleaning - the unit has been ordered (139€) and the total bill for supply and fitment will be 208€. Booked in for 10 days time.

I will let you know how it goes....


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## sheds (Nov 6, 2005)

Thanks for a new angle of attack Drew. I'm no good with electrics and I just checked for a current flow, ot really knowing what I am looking for. I also fitted new terminals on the valve end but will take a look at the controller too. I'm guessing that if I connect my multimeter one end to the spade connector from control unit, the other to the terminal on the valve, I should be able to see 1 volt. I shall try this and report back! By the way today I disconnected the gas supply to the valve and checked that there was a flow to the inlet - phew there was so at least it isn't a problem with a damaged pipe somewhere behind the kitchen units.


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## sheds (Nov 6, 2005)

Ouch Penguin! I glibly thought that at £150 + for a new valve it would be cheaper buying a new fridge................until I looked at fridge prices!


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## sheds (Nov 6, 2005)

Well it sounded like a good idea, but I measured 1.4 volts across two of the connectors and none on the third. I assume the third only passes a current when the solenoid switches.....So it looks very much like a new valve and finding a professional to fit it somewhere in the Reading area!


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## Penquin (Oct 15, 2007)

The Dometic engineer who looked at mine used the left hand knob and twisted it further clockwise and that allowed the gas to flow, but when he released it the flow stopped and he immediately said "control unt" he was 100% convinced......

Might be worth trying......


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## LT Man (Nov 11, 2016)

Has Sheds seen any of this and is the fridge fixed ? That is what i want to know

LT Man


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## Penquin (Oct 15, 2007)

Wel his last post was at 1517 today, so the answer is yes he will have seen the thread, but his last comment was less positive about it working. I think....😢


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## sheds (Nov 6, 2005)

Sorry - Yes I have followed up all the suggestions and tested the volatage going to the unit at 1.4v. I disconnected the gas supply pipe to the valve and confiorm that there is a flow of gas, but not beyond the valve. Tried much hammering to free off the unit and no joy. Now it is time to admit defeat and locate a Dometic engineer in the Reading area. Meanwhile I have moved on to the mysteries of a front brake pad change on the base vehicle - a 2007 X250 3.0L Ducato. Having always done my own car maintenance I wrongly thought that this would be an easier job........of course in those days I had Haynes manuals to help me!

When I find a Dometic engineer who can come to me or who is within easy driving reach I will let you know the outcome of the fridge problem


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## sheds (Nov 6, 2005)

OK It is now mid April and mid lockdown. I finally bit the bullet and bought a new valve for £120 odd smackers. I fitted it myself (will get it safety checked when I can get to a gas qualified fitter) turned the gas on to the fridge and it fired up immediately. You could say I am well pleased! Thanks for all the help and advice.


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