Thetford fridge not working on gas (1 Viewer)

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Bart

Bart

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I refer you to my previous reply:
"Thetford fridges don't use a thermocouple, they use flame rectification to detect combustion. Once the flame is lit the ionized has in the flame conduct to earth from the electrode. The reason yours is still sparking once kit is that the flame failure circuit has failed. This might be due to a dirty electrode or the burner itself may be partially obstructed causing the flame to not hit the electrode, if none of the above them it's likely to be the main pcb which is about £150 or so."

D.
Yip Dave thanks for the info / help and yip a new electrode is ordered , but obviously with holidays it will not be here until new year :( , lets hope that is the problem as i have noticed that the spark / electrode part at the end is able to rotate and drop down onto the top of the burner thus reducing the 4mm gap between the electrode and the burner to like 1mm.
Its like the wire that runs up through the middle is no longer fixed to the center of the unit and is allowed to turn inside the unit.
 
Aug 6, 2013
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Dave's replies or your own final comment will lead you to the fault. It cannot be caused by any other sensor.
 
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Bart

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btw i ran a separate new earth from the cab battery to the screw that screws into the burner assembly and holds the electrode in place , in case a poor earth was a contributor but it made no difference so i take it that rules a bad earth out or did i need to run it from the habitation battery ?

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Bart

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So today my new electrode arrived for the fridge :party2::party2:
Took a whole 5 mins to install as i still had the cover over the main pcb at the rear removed.
I turned the fridge on and and i could see click , click , click , click ,from the electrode then the fridge lit up as normal and the clicking stopped ( meaning it had sensed the flame ) , i left it running for 5 mins and well chuffed that it was fixed , so i stopped it , then i thought i had better check it for longer so i did the same as above except this time yip you guessed it the bugger just kept clicking after the flame had been lit , then auto shut down after the 30 secs. :banghead::banghead:
Am i right that be me running an earth wire from the leisure battery to the screw on the electrode that itself screws into the metal burner assembly will rule out a bad earth ??
I just want to make sure that i have done everything possible to rule out anything else before i take the final step and buy a new main PCB at £150.
 
Aug 6, 2013
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No. Not worth the effort. A 'bad' earth for this purpose would need to be no earth at all. Not sure why you thought a new electrode would help - an old nail would do. Which model Thetford is it?
 
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Bart

Bart

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I have just been looking the Thetford trouble shooting pdf for error code 9 to make sure I have tried everything prior to changing the board, that is when I noticed it says to check the gas pressure is between 28 and 30 mb...
I have no way of checking this, but surely if the gas lights perfectly everytime until it gets auto cut off after the 30 seconds, then the gas supply should be OK?
You can see a you tube clip of the flame at the start of this thread.
https://caravanchronicles.files.wordpress.com/2013/03/troubleshooting-fridges.pdf

IMG_20180105_224807.png
 
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Bart

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Thanks - l just wondered what the controls comprised. If you do need a power board (and its looking that way) these people have them:

https://www.leisureshopdirect.com/c...d-n180-fridge-spare-parts#ppSpecs[iframes]/6/
Yip thanks , today i have been looking between them @ £140 but they are charging £18.99 P&P
or one on ebay for £145 with free P&P , only thing i wonder if there are different revisions of this PCB as the one at leisureshop says "Power Board A V3" in the description so i'm wondering if the "V3" means revision 3
if they are all the same then ill order it from oasis as its free p&p for £5 more , but saves me £19 on p&p :Eeek: :Eeek:

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Bart

Bart

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The new replacement board arrived yesterday, I installed it and it worked straight away, left it until today and tried it again and yay loads and loads of testing later and it seems fixed :)
 
Dec 9, 2018
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Hi, Just joined this thread as I have the same problem on my 2011 Auto-cruise Startrail. Having gone through and checked all the possibilities mentioned above I have ordered a replacement power board.
Is it possible to remove the housing and the power board on the back of the fridge from outside through the lower vent on the motorhome or do I have to remove the whole fridge and remove the housing and power board inside the van?
 

TerryL

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Interesting thread as I have a similar "problem" on my virtually identical Bolero, except that it only happens when first lit after standing for a while with the gas off - I'm talking of weeks, in storage. In my case however I just switch the fridge off, wait a few seconds and try again. It invariably is okay on the third try, I've put it down to the gas pressure needing time to build up.

@bingoking looking at it it maybe possible to leave the fridge in situ but it'll be a right fiddle as a couple of the retaining screws on the cover are on the side of the housing. Having also taken the fridge out 3 times (once to tighten the previously mentioned grab rail screw - who designs these things? - and twice replacing the 12v element due to wrong part supplied) it's not all that bad. Take care disconnecting the gas pipe as mine wouldn't go back properly and the joint had to be remade. Also take a photo of the electrical connections before you disconnect. A crate to take the fridge as it comes out is definitely needed, there's so little wiggle room and the fridge is too cumbersome for one person to handle.

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Dec 9, 2018
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@TerryL Thanks for your reply. I did have a look and it does look a bit fiddly to work from the outside but just wondered if anyone had managed it. Taking the fridge out might be the best idea to save my knuckles x:-)
Good idea to take a photo of the electrical connections, I had planned to do that.
Thanks again
 
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Bart

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Just updating this thread for anyone in the future having similar issues
It's now been 15 months since I replaced the PCB in the fridge and I can say the fridge has been working fine.
 

Evildoody

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Nice one Bart, I have an ongoing issue with my Thetford N3150 not cooling on gas - looking at the flame from your burner that really does suggest that my flame is no where near as ferocious as it should be, away to fit a new burner so hope that solves my issue.

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Bart

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Nice one Bart, I have an ongoing issue with my Thetford N3150 not cooling on gas - looking at the flame from your burner that really does suggest that my flame is no where near as ferocious as it should be, away to fit a new burner so hope that solves my issue.
Hopefully will make a difference, its easy to change as well anyways
 

Evildoody

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Yes got the new one ready to fit, fingers crossed as I am going to a festival tomorrow evening :D2
 

Evildoody

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You're very welcome.

D.

Hi Dave, not quite sure who you are acknowledging on this post as I was merely thanking Bart for his video of the burner flame in the very first post, I didn't read through the rest of the thread as the particular issue I have is not quite the same as the OP's. Sorry, just got a bit confused with your last post :)
 

Trav76

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Hi all. New to the group and given there seem to be so many knowledgeable people here, I decided to bombard this thread with a problem in having with my Thetford 3 way fridge on gas. I ran it on 240v prior to my trip and it froze everything in the fridge and freezer. (Which was fine ). Swapped it over to gas and had a difficult time getting it to stay lit after I removed my finger from the button. Had to keep my finger on for more than 5 minutes! It would go out if I removed my finger too quickly.
Mine has a manual ignition. Needle rose to the green section of the dial eventually, indicating flame lit but wasn’t getting cold.
Without moving the van, ran it on 240volt and it got cold again. Took the covers off and started it on gas, inspected the flame lit but again not cold.
Removed fridge and inspected gas lines and all appeared ok. Reinstalled and ran it in gas and all seemed ok.
Given it was so hard to initially light it, could my thermocouple have an issue ? Or can a faulty thermocouple allow a flame that isn’t hot enough to achieve coolness?
 
Apr 22, 2018
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What state/appearance does the flame have once alight?

Should be a nice bright blue flame and you should be able to hear it.

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Trav76

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What state/appearance does the flame have once alight?

Should be a nice bright blue flame and you should be able to hear it.
Yeh the flame is blue and seems bright enough. (I can’t hear it though.) It has a dial with settings 1-5 and this actually varies there flame intensity. I’m starting to think it has some sort of intermittent fault on the gas side. The the flame indicator always reads correctly. I’ve attached a short video.
 
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if its the same as a dometic its probably just the gas jet thats blocked ,its inside the supply to the burner lots of nutube to show how
 
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88949

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We kept getting the same error code (9) when trying to run the fridge on gas. The burner would light but then go out again when the igniter ceased sparking. The fridge had not been used during the pandemic and an insect must have crawled up the burner and laid some eggs. When the pupa hatched, it left behind the sack that had enclosed it. This obstructed the gas flow causing the flame to blow back out of the burner air inlet. A rake around with a length of soft copper wire retrieved the sack and the fridge has worked fine ever since.

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8

88949

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We kept getting the same error code (9) when trying to run the fridge on gas. The burner would light but then go out again when the igniter ceased sparking. The fridge had not been used during the pandemic and an insect must have crawled up the burner and laid some eggs. When the pupa hatched, it left behind the sack that had enclosed it. This obstructed the gas flow causing the flame to blow back out of the burner air inlet. A rake around with a length of soft copper wire retrieved the sack and the fridge has worked fine ever since.
 
Oct 22, 2022
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Hi everyone. I've just been having the same issue with my fridge. Followed all the steps, including removing the thermocouple and cleaned it up. Miraculously, the fridge then burst into life. Lets hope it stays alive for our trip to France!!
 

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