Thetford N145 no longer working on 12V

Discussion in 'Fridges & Ovens' started by Evildoody, Aug 9, 2018.

  1. Evildoody

    Evildoody Funster

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    Hi all,

    My fridge has just stopped working on 12V, still works fine on 240V and Gas.
    All was working well for a 5 hour drive yesterday, but today the LED on the panel indicating battery is flashing once a second. Vehicle battery is fully charged and I have checked voltage (with engine running is at circa 14v at the back of the fridge). Initially I thought it may have been a fuse, so I checked every one I could find in the vehicle and all are ok. But this morning I switched the fridge on and SES automatically selected battery, however it only ran for a couple of hours before flagging up a fault again.
    The fridge does not have an LCD so I am not sure what the flashing LED indicates as a fault.
    This intermittent fault at least tells me it is not a fuse, any tips/suggestions?
    Does it sound like a loose connection or perhaps a circuit board on its way out?

    Thanks.
     
  2. icantremember

    icantremember Funster Life Member

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    Probably the 12v heating element has blown.
     
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  3. WillH

    WillH Funster

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    Agree with above answer, fit new element. Cost around £30.
     
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  4. Evildoody

    Evildoody Funster

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    Great, thanks guys - I will get one ordered :).
    Another quick question, where exactly on the back of the fridge is this located and is it likely to be changeable in situ via access through the external vents as opposed to removing the whole unit?
     
  5. Evildoody

    Evildoody Funster

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    Did some investigation, looks like I am taking the fridge out - looks straight forward enough.
    Disconnect power/gas/12V/240V cables etc., remove internal fridge screw covers, remove screws and slide fridge out. The following video should prove helpful.

     
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  6. Reallyretired

    Reallyretired Funster

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    I replaced one on an earlier motorhome through the bottom vent with the fridge in situ. Depends on fridge model and size of vent.
     
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  7. Evildoody

    Evildoody Funster

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    Well I had to remove the fridge :-(. The DC heater element is out now. Job next weekend is to fit the new one, test, refit fridge and reseal.

    Some pics of the fridge and circuit board - Fridge is a Thetford N145A

    IMG-20180811-WA0003.jpg 20180811_131339.jpg 20180811_131352.jpg 20180811_131455.jpg 20180811_131503.jpg 20180811_131538.jpg
     
  8. Evildoody

    Evildoody Funster

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    Damn it, changed DC heater element, same issue :cry:.

    Posted a video of the LED's on the panel, hopefully someone can tell me what they mean?
    (Yes, vehicle engine is running and DC voltage to fridge is at Alternator voltage)


     
  9. DP_JAY

    DP_JAY Funster Life Member

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    What happens if you manually select 12v instead of AES?
    Though I must admit it's looking like a circuit board fault.
     
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  10. Evildoody

    Evildoody Funster

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    Same issue mate, LED goes solid green for a few seconds and then starts flashing, then the RED warning LED starts flashing.

    Yeah, I now suspect the circuit board too. Was worth changing the £30 part though before changing a £150 circuit board. Oh well at least the new circuit board will be the newer model :)
     
  11. tonyidle

    tonyidle Funster

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    Before changing anything else ensure that the 12v supply to the element is still 12v under load. You said the supply to the element was OK originally so assuming nothing has changed if the supply is still there, at the element, the fridge will work. For it not to work either the supply isn't there or the element is faulty.
     
  12. Evildoody

    Evildoody Funster

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    I assume by element you are referring to the DC heating element? - if so then we can probably rule the element out as the fridge is showing the same fault with the new one fitted, so your thought is that this could still be a voltage supply issue as opposed to the circuit board? If so I will stick the multimeter on the DC heater terminals of the circuit board while I get someone to switch the fridge on with the engine running.
     
  13. tonyidle

    tonyidle Funster

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    I thought from what you said at first that you had checked for 12v at the heater and that it was OK. Which is why, quite reasonably, you believed the element had failed. Having changed the element it should therefore work. It doesn't so that leaves the 12v supply. A 'problem' with multimeters is that they'll read a voltage through a piece of wet string (or a corroded connection or fuse) whereas a decent load, like a bulb or an element, will see nothing. If, however, the circuit board does prove to be faulty take a look at it before buying a new one. Water can run down the wires that enter from the top which might have caused repairable corrosion. Seal that area once you have the fridge working again.
     
  14. Evildoody

    Evildoody Funster

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    I measured the voltage at the DC heater terminals today, got a helper to switch the fridge on to DC while I had the multimeter connected, with the engine running I was reading 13.6V at the DC heater element terminals, I could hear a relay click, click again and the fridge presented the previous error.
    Tried switching the fridge on and off a few times and it eventually started working on DC (albeit for 5 minutes) before erroring again. Voltage dropped to 12.5V whilst fridge was running. I think this is looking more like a power board issue?, I could be wrong so if anyone has a suggestion - please let me know.
    The power board on this fridge is the V1 and I can't find a spare for sale anywhere. I don't want to spend £1800+ on a fridge to fix a problem running on 12V!!! :cry:
     
  15. hilldweller

    hilldweller Funster Life Member

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    >>> Thetford N145 no longer working on 12V

    Sign of the times innit.

    Try offering 13V knowing if push comes to shove you can go to 14.1V
     
  16. DP_JAY

    DP_JAY Funster Life Member

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    Got our parts from leisure shop direct.
    Found them very helpful when ours packed up (gas faulty)the day we were going away. They let us collect the part from them.

    https://www.leisureshopdirect.com/c...thetford-smart-energy-selection-model-fridges
     
  17. Evildoody

    Evildoody Funster

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  18. DP_JAY

    DP_JAY Funster Life Member

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    I know, when we got ours it was the modified one with a new box, instructions etc. I still have the old one & all the instructions s etc. If it helps I'll dig it out tomorrow.
     
  19. Evildoody

    Evildoody Funster

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    If you don't mind, that would be great - I was not sure the new board is interchangeable with the old one - I have had a look online and some of the plug sockets are totally different on the new board.
     
  20. DP_JAY

    DP_JAY Funster Life Member

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    No problem, it'll be afternoon when I get up off nights.
     
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