3 Way Fridge will not run on Gas

[daver]

Hi, apologies if this topic has been exhausted before.

I have a Dometic RMD8555 AES 3 Way Fridge which has stopped operating on Gas. 230v and 12v OK. Neither AES or Manual selection of Gas will start the ignition process. With removal of 230v and Gas supply on and primed there is a clicking from the back of the fridge (bottom grill removed) which sounds like a relay or switch cycling. The AES display on the front panel dims and goes bright in unison with the clicking. No red failure light on panel. This is not the ticking of the igniter but seems to be coming from the covered control panel board. All wiring appears to be in good order. I’m thinking it could be the P810 Burner Control Device. Does anyone know how to check this item before I change it. Not cheap but loads available which is suspicious and leads me to hope it is this. Any help would be appreciated.

[Labby]

It could be worth checking that the ground terminal on the gas burner is clean and good in case a poor ground connection there is causing this problem.

[daver]

Good idea thanks. That is the one ground I haven’t removed. Probably because it is behind that shield. 

[daver]

Labby. Just as a follow up for info: I have no earth terminal on the burner despite the wiring diagram showing one from the burner control device. Took the cover off and just the two electrodes. The feed from the control board to the burner control device also doesn’t have a black feed as per the diagram so not sure what is going on here. Certainly used to work fine on Gas configured like this. Guess I’ll have to contact Dometic to see what they have to say about it. Cheers for your input though. 

[Labby]

daver ,  I think you may have the later control module (P-860 ) and controls , 2012onwards, and the wiring diagram you have  is for the earlier version of your fridge (the later version does not have the ground cable to the burner)

[Globebuster1]

Those burner control units [the brick as it's known] are notorious for failing.

I have had to replace mine on the RMD Tec Tower version - mine was a potted unit so you can't even see inside.

The back of mine was discoloured [heat damaged] where obviously something had been going on.

Either that, or give the gas valve a sharp tap - that's been known to fix a non-igniting burner

[daver]

Labby

The Motorhome is 2012 but the Burner Control Device is definitely a P-810. Clear by photograph. Right on the change I guess. 

[daver]

Globebuster1

Thanks. I’ll try the tap method. Coming round to thinking it is the Brick mind. Cheers

[daver]

Happy to report that following Globebuster1’s advice a sharp tap to the gas valve resulted in immediate ignition and light up. Thank you. I have learnt a lot about this AES fridge from this escape so nothing lost. If the problem persists I’ll get the gas valve replaced. Otherwise I’ll make sure the fridge is functioned periodically on gas. Hope this might help others.

[Globebuster1]

Good News!

Hope that's the end of the matter, if you don't use the gas option often - always cycle through the gas and 240v manually from time to time.

Even with a new 'brick' installed, I sometimes get a failure on 240v after a few hours - no fault codes!

I've now got into the habit of firing up on gas for an hour, then switching to 240v then it's perfect for days on end.

These fridges are not the greatest, and the AES function seems to have a mind of its own!

[Brian Kirby]

As you've found the item is fairly widely available, but costly, it seems the above advice (plus travelling with a gas solenoid "whacker") is the best all round strategy.  After all, were you to try to eliminate the problem by installing a new solenoid valve, it is always possible that, too, may begin sticking.

I assume there may be a question as to whether the newer version (which I assume you'd now get) is readily interchangeable with the version on your fridge, and whether that missing ground connection is easily made good. 

Against that approach would be if the solenoid valve were to fail completely while you were away in the van, and whether you could then actually get a replacement valve delivered before having to dump the fridge contents - especially if outside the UK.

However, as it seems you do not use the fridge extensively on gas (suggesting you generally stop on sites), and as it functions satisfactorily on 230V/12V, even were the gas valve to totally fail you'd only need to head for a campsite (or possibly an aire or similar if abroad) and plug in until the new gas valve arrived, so more of a nuisance than a disaster.  I think, overall, stay with Plan A - and a whacker!  🙂 

[daver]

Thanks Brian. As an aside  I use Autogas and note a warning in the Dometic manual that 6 monthly cleaning of the flue is recommended when using this type. Just wondering if Autogas may have contributed to the sticky valve? I don’t think so but it clearly burns differently so who knows 😊.