Dometic fridge not working on gas or 240V

I have a Dometic RM 7271 3 way fridge,  product Code 00921084155 fitted to a 2005 Autosleeper Nuevo. The fridge is intermittently not working on Gas and Elec (I don’t know if it works on 12v or not). I have checked the gas supply (via the gas hob) and that the 240 power is on (the circuit breakers are all on and power is getting to other appliances. The van is level.
I have tried to establish a pattern over several days.
Gas: When I turn the switch to gas on the front panel of the fridge it mainly fails to ignite. (I can see the burner via the ventilation panel). Occasionally it will ignite (I can hear it and can see the burner is lit). However it will only stay lit for an hour or so before it goes out. It usually will not ignite again for a period of time. When it is lit the fridge does start to cool down (I use a thermometer) so I am reasonably confident that the fridge itself is working. One time it did light was when I moved the on off switch backwards and forwards quite quickly, but this only happened once.
Elec: Most of the times I switch to Elec it does not come on. Sometimes it does come on but not often I know when it has switched on because the heating element on the back of the fridge gets hot. When it doesn’t work it stays cold.
It seems to me that the communication from the control panel to switch on the fridge (either gas or Elec) is not working properly. Is anybody able to comment on this or to point me in any other direction on it?

It is odd that you are having issues with both gas and 230v. 

I suspect the gas it lit from the 12v Side so makes little sense.

The 230v switch is a big green one (larger than the others) and has a light in it when it is on. Obviously you need the temp dial turned up so that it will stay on. If not it might be getting to temp and switching off.

Are you sure you have the temp nob on the gas turned to cold also.

I am wondering if you are turning the temp control knobs the wrong way as I know they are a little confusing

I have a slightly newer Dometic Fridge but the internals look very similar.  Below is a picture of what should be your control panel.  If you can find and get at it (make sure no 230v connected to the van) you will find cable connectors where I've put the yellow arrows (and other places as well).  The connector makes contact with the board via connection points that are part of the board.  These get dirty.  Carefully clean the connectors and contacts with cotton bud and saliva and you will likely clear the gas fault and maybe the 230v as well.

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Thanks to both of you for responding. There is only one temperature control knob and I am sure it is turned the right way.

Peter: Do you think I should be able to gain access to the control panel by removing the On / off switch and the temperature control knob? I am guessing that there will be some retaining screws in there. I don't have a lot of knowledge on this but from the patterns I am seeing the logic to me is that the signal from the off / on switch is intermittently failing. Hence; not switching on and / or switching itself off. If I can get the front off I might be able to clean the contacts. Picture of the front of the fridge below:



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Oh mine in my 2004 Nuevo is older and different than that

Thanks Bigplumbs. No problem

HI Bernie. It Is not clear from your original post whether the indicator light on the energy selection switch is lit on the occasions when not igniting. When gas selected it should blink and you should hear a clicking sound until it ignites at which time the indicator light is permanently on. When 230v selected it should be permanently lit. If this is not the case I think the problem is likely to be the switch on the control board that Peter describes. Mine failed on the 6v setting. Prior to failing it made a buzzing noise.
To access the control board you will need to move the fridge out a little to gain access to the top. To do this you will need to remove 2 retaining screws, one each side of the fridge. Usually there is sufficient give in the gas line and electrical connections at the back but check this via the outside vents.

Bernie Johnson wrote:Thanks to both of you for responding. There is only one temperature control knob and I am sure it is turned the right way.

Peter: Do you think I should be able to gain access to the control panel by removing the On / off switch and the temperature control knob? I am guessing that there will be some retaining screws in there. I don't have a lot of knowledge on this but from the patterns I am seeing the logic to me is that the signal from the off / on switch is intermittently failing. Hence; not switching on and / or switching itself off. If I can get the front off I might be able to clean the contacts. Picture of the front of the fridge below:

Im not familiar with your installation of the model that preceded mine, but I expect it should be possible to bring the fridge forward enough to remove the control panel without disconnecting pipe or cables. Take the external vent covers off and make small moves checking front and back all the time.

I had exactly the symptoms you describe for gas intermittently for six years with several Dometic approved engineers replace various parts. Eventually it failed completely and my local mobile engineer phoned a retired Dometic Engineer well known to him who said it was most likely the cable between the ignition box and control panel. Whilst waiting for a new cable to arrive I accessed my control panel, found the unreliable connection system, cleaned the connectors and cleared the fault.

Thanks to you both. I do think we are on the right track and it seems to be pointing to a switch problem. Although, would this be responsible for the gas and elec just cutting out within an hour each time? One other thing that may or may not have a bearing is that the temperature control switch moves very freely when turned, as though it is not gripping anything. I have tried both gas and elec quite few times now since yesterday morning. The fault is very much intermittent. This morning I did the following:
 
8am. Gas ignited first time
8.30. Still lit
9.30. Not lit
10.30. Retried. Nothing.
10.30. Turned off gas and elec. Took plastic cover off control unit
Without taking CU out moved cables I could reach slightly . Moved switch to gas. Could hear Ignition and light was flashing. Turned gas on and burner lit immediately. Left to see how long it stays on.
11.30. Burner not lit
12.00 still not lit.
Tried to reignite.  Nothing.
Turned gas off and turned switch to on. No attempt at Ignition and light not flashing.
12.20. Nothing on gas. Tried elec. Within a few minutes the heater at the back of the fridge got warm . On each occasion have tried elec it is intermittent like the gas and cuts out within an hour but have now left the elec on to see if it stays on.
I have the ventilation panel off on the outside and can see onto the top of the fridge now from the inside. It does look to me as though there is sufficient play for me to move the fridge out (carefully). I guess I have no choice but to try. The irony is that before I started researching it, to me the fridge just wasn’t working so I had an engineer visit. Although he did nothing different to me the damn thing just worked on both gas and elec. Unfortunately he didn't experience it cutting out. He suggested that it might not be working as the van wasn’t fully level (it is now and the fridge cools, when I get it on!).

Bernie Johnson wrote:The irony is that before I started researching it, to me the fridge just wasn’t working so I had an engineer visit. Although he did nothing different to me the damn thing just worked on both gas and elec. Unfortunately he didn't experience it cutting out. He suggested that it might not be working as the van wasn’t fully level (it is now and the fridge cools, when I get it on!).

I had that several times as well. Theories include wind angle, quality of gas, sorcery etc. Gas valve, ignition controller and burner all replaced over time - each time it seem ed it was fixed then a few months later back to being intermittent. Its worked perfectly on gas (and 230v & 12v) since the control board contacts were cleaned - I did also replace the cable from the ignition box to the control panel as I'd paid for it but don't think it was needed.

My money would be on the mulitfunction switch as I repaired a similar two-knob Dometic fridge in my friends 2004 Autotrail that was doing the same thing some three years ago It had been back to the dealers quite a few times and despite them changing almost everything else (sometimes twice!), and at enormous cost, they had failed to cure the problem.  A new switch would have cost over £120.00, but it was out of stock everywhere, so although it was a bit of a gamble I decided to try a 'Repair Shop' thing and carefully stripped down the old switch down after making lots of notes and taking photographs of where the wires went. Inside were lots of springs and metal contacts and I found most of the silver plated contacts were tarnished, so a quick clean up of all contacts with a fibre glass brush and a light coating of petrolium jelly soon had it working reliably again.  Obviously this is not something a dealer or 'trades' person would attempt, but the switch has been working reliably now for at least three years, so it was worth a go if you are feeling brave, and even if you fail you can always fit a new switch.  Downside is you have to pull the fridge out to gain access to the back of the front panel to do anythingwith the switch etc.

Hi Barryorbik. Thanks for your input. I'll bet you are right. However, I decided to replace the power board completely. I have an engineer recommended to me by a friend and he has ordered the part. Just waiting now for him to receive it and fit it.

Hope the new board cures it Bernie, and don't forget to post the result !

With 3 way fridges (I have the 7291L in my 2007 Nuevo) the common ground to the 3 systems is yes the electronic panel which you have ordered.
BUT first port of call though, have you had the fridge serviced? This has to be done by a reputable motorhome/caravan workshop who have a registered LPG operative. It my be the electronic board but I would have the fridge serviced first as during this process it will confirm if the board is at fault. As with most repairs it's a process of elimination till the fault is found. To me just ordering the board which is expensive may not be the fault for some of the reasons below. All the below would need the fridge removed from it's cabinet.

GAS system
Down by the burner assembly there is a jet with a very small hole in it. The jet over time can become slightly blocked with dust etc and it is usually best to replace it. The burner assembly may also need cleaning as again they can also become clogged. The sensor probes could also be miss aligned. Any combination of these problems can cause intermittent ignition and running. During the service the flue tube is also cleaned with a wire flue brush as again it can develop flaky debris over time and can effect the chilling process.

240V
The 240v element which sits along side the flue tube (with the 12v one as well) inside the large metal surround which is full of fire retardant insulation needs to be checked that it is still functional and has not blown. A continuity check (with a volt meter) along the two feed cables (with no mains electric connected at all) will confirm this. If no continuity it's blown and needs replacing.

12V
The same goes for the 12v element, check the continuity to see if it's blown. If it's ok now check if there is a 12v feed which is only live when the engine is running. This feed is operated by a 12v relay which switches when the engine starts.

I'm retired now but used to work in the caravan and motorhome industry for some 35 years.

Thanks barryorbik and Gollum. I am committed to replacing the board now which hopefully will be soon. I'll post the results and if it is still a problem I'll get the fridge serviced as per your comments Gollum. NB. The engineer is fully qualified so hopefully we will get there!!