# Thetford Fridge 12V Operation - What switches the 12V On



## Ken38 (Mar 24, 2009)

I am trying to find out what is wrong with my Thetford N100. To help my understanding does anyone know what switches the 12V on when the vehicle runs.
I just had the engine throttle "propped" at 2000 rpm but it still sat there with the blue light flashing and a code 9, engine not running! My wife says the blue light normally stops when we are moving as she can see it from her seat. I can't quite believe the vehicle needs to be doing more than charging the battery from the alternator for it to run on 12V!

The fridge is working on 230 Volt at the moment but will not work on gas either. I am trying to understand the operation a bit more so I can "grill" the professionals when I get them involved. Which will be soon!


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## steco1958 (Mar 5, 2009)

Ken,

There is a sort of fixed relay contracption, with also 2 permanent + , -.

It gives you some good information of the leaflets that come with the fridge.

I have an error code 2 that is showing on mine, however its all under warranty and the mobile guy we use is coming over on Wednesday next week.

Steve


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## drcotts (Feb 23, 2006)

Hi
I assume its a 3 way AES fridge.

if the code shows that theres no 12v at the fridge then the causes are probally

Fuse blown
PCB board under the fridge has gone
12v element has failed

The last one was the case in my fridge less than 2 yrs old.

I have the number of an excellent caravan fridge engineer engineer if you need it. Pm me and I will send you his no

He is based in Coventry but travels but charges per mile but if you are not desperate he will wait till hes in the area and charge you from the next call.
hes a really knowlegable boke about caravan fridges and will spend half the time telling you all about how it works

Phill


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## steco1958 (Mar 5, 2009)

Dr Cotts.

Actually it wasn't any of those !!

In the EM50, where the electrical control from Fiat is handed over to the motor home electrics. there are several fuses on top, however underneath, there are push fitting plugs into the PCB board, one of those had worked loose.

I have to thank Sargent Electrical Services Ltd (Clive) for pointing me in the right direction.

Fridge now working on all 3 supplies.

Just need to cancel the fridge engineer and all is well with the world, for the moment anyway.

Steve


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## Ken38 (Mar 24, 2009)

After a bit of pushing I got a partial wiring diagram from Hymer. I could then check out the 12V supply to the fridge. That looked fine but the fridge did not cut in. I gave the MH to a local dealer and with Thetfords confirmation they found the control board was faulty and replaced it at significant cost. The fridge is now fine and when 12V is selected works on 12v as soon as the engine is running.
Now I understand how the circuit works it is clear that the fridge has not worked on 12V since I bought the van second hand from Brownhills.
Worse is the fact that I asked Brownhills to check the fridge after I had had the van for while and paid for the privilege as they said the fridge was working correctly!
Two hours labour and a new board £260!


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