Thetford N3xxx Fridge Error Code 8 on EHU

Hi folks. 

We have the Thetford N3xxx fridge in our 2016 Broadway EK. 

Everything had been fine until this week, fridge always runs on Automatic but noticed our LPG was running out faster than normal. 

On checking spotted the fridge was on Gas, despite being on EHU. 

Manually shifted to Electric and got the Spanner with Fault Code 8. 

Looking up this suggests “Error code 8: AC heater current is measured to be 75% below nominal current.” 

I’ve tried powering it off for 30 mins, changed EHU to another pitch and tested with another cable. Also checked the 5A fuse and replaced it anyway inside the Sargent. The MCB says fridge / boiler and charger a d 2 out of 3 are working

Further research also suggests a Glass Fuse in the back of the fridge accessible via the lower vent inside a power unit. 

I have contact Marquis, who are willing to take a look at it as the motorhome was purchased 11 months ago and still under their warranty BUT that’s a 300 mile round trip and I’m not sure I expect them to resolve it on that trip so probably a second 300 mile trip getting very close to warranty expiration. 

So just wondering if anyone has any other ideas I can looked at before going back to Marquis with it. 

Many thanks

Jason

When we saw that failure code, we were on holiday in Cornwall, so, we got a mobile tech out to take a look. He confirmed power was getting to the fridge OK and diagnosed a faulty board. As it's a fridge out job, we opted to wait until we were home - our usual workshop confirmed the issue and replaced the board.

If it really is a glass fuse in the back of the fridge, then it should be a very simple DIY job - there should be nothing complicated at all about it, and the time needed should be trivial compared to a 300 mile drive.

However, I've never come across a 3-way fridge with a fuse in the back. If you have the complete model number (I assume N3xxx is not the actual model number) then it should be easy enough to find the documentation online and confirm whether there is or not.

There will not (or there should not) be an inline glass fuse in the wiring - that would not (as far as I'm aware) be permissible for a 240V supply.

Jason,

From reading your post it sounds that you’ve found Thetford’s diagnostic guide for the N3000-series fridges, specifically the fault tree for Error Code 8. 

The fuse referred to there is mounted on the power board, which is located behind a cover at the lower rear side of the fridge. Access is via the lower outside vent aperture. Getting to the fuse requires removal of the board, which in turn requires cables to be disconnected, none of which is easy.

I’ve been through the Code 8 scenario and with the help of Thetford’s Tech Helpdesk traced the problem to a faulty 240V heater element. The elements burn out after a few years of use and go open-circuit, and this may well be your fault too. If you’re confident at using a multimeter then it’s far easier to check the element than it is to remove the power board to check the fuse. Thetford’s diagnostic guide tells you the resistance range for the element in your particular fridge model.

I wrote up the process I took to diagnose and replace the element at the link below. Unless you’re happy to go into the rear of the fridge with tools then you may want to get Marquis’s approval to get a mobile technician to fix the fault given the distance involved. One option might be to check out the element using my notes and pictures. If you’re able to establish it’s gone open circuit then you have good information to put to Marquis and negotiate getting it replaced locally and claiming back the cost from them.

Tim

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Jason,

From reading your post it sounds that you’ve found Thetford’s diagnostic guide for the N3000-series fridges, specifically the fault tree for Error Code 8. 

The fuse referred to there is mounted on the power board, which is located behind a cover at the lower rear side of the fridge. Access is via the lower outside vent aperture. Getting to the fuse requires removal of the board, which in turn requires cables to be disconnected, none of which is easy.

I’ve been through the Code 8 scenario and with the help of Thetford’s Tech Helpdesk traced the problem to a faulty 240V heater element. The elements burn out after a few years of use and go open-circuit, and this may well be your fault too. If you’re confident at using a multimeter then it’s far easier to check the element than it is to remove the power board to check the fuse. Thetford’s diagnostic guide tells you the resistance range for the element in your particular fridge model.

I wrote up the process I took to diagnose and replace the element at the link below. Unless you’re happy to go into the rear of the fridge with tools then you may want to get Marquis’s approval to get a mobile technician to fix the fault given the distance involved. One option might be to check out the element using my notes and pictures. If you’re able to establish it’s gone open circuit then you have good information to put to Marquis and negotiate getting it replaced locally and claiming back the cost from them.

Tim

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No idea why my post appears twice!

After reading Kemerton-Bath's post, I've checked our paperwork and we also had a failed element, not the board as I'd said above.

Hi Tim. Thanks for the post and the very detailed link you supplied. 

Like you my fridge is N3097, I had to go looking for the exact number. 

I do have a multimeter and once home at the weekend can look at testing the element and go from there. Looking at your instructions, I wouldn’t be confident to do that job myself but your point about either providing Marquis with the element test info or agreeing them to approve someone more local to do it. 

For now we will get by on Gas and I’ll study the instructions and look to do more when home after this trip. 

Thanks very much Tim for all the details. 

Jason

Hi Tim, just wanted to update and say thanks for all the info. 

Was able to diagnose the heater element as faulty and found Premier Thetford place 12 miles from home. 

Job done for under £100 and when I explained the situation to him he also called the warranty company and I was able to obtain and authorisation number for the work. 

Fridge now working again on electricity, didn’t need one, potentially two drives to Newcastle and back. 

Thanks so much for the info, this forum really is a great place 

Thanks again

Jason

Jason, that’s a great outcome, thanks for closing the loop.

Keeping a multimeter in the vehicle and having the knowledge/confidence to use it when kit goes faulty is a big help.

Tim

Hi thanks for the detailed instructions had a similar problem ordered the part and fitted using your instructions. Little fiddly to find the correct position to replace the elements but done in around an hour  cost £37 thanks again

Hi I’ve just returned from our first trip in 2 years and encountered the same problem, although my manual refers to ‘ below 80% nominal power’. Is this the same?
I had the same problem on our previous trip although after a couple of hours it returned to mains for the rest of the week.
I had it checked by a reputable motorhome centre and they said it was okay. Do I need a new service centre;-)

Thetford’s fault finding guide for the N3000 series doesn’t refer to “below 80% nominal power”.  You possibly have a different fridge, in which case you could maybe clarify.

You might get more responses if you follow the forum etiquette and introduce yourself.  See link below.

Tim

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