Thetford fridge (1 Viewer)

[pagey]

Hi does anybody know which 2 wires supply 12 volts to the fridge when the engine is running I don't think mine is working its OK on gas and ehu thanks

 

[Lenny HB]

An educated guess the Red & Brown, only ones large enough to supply the current without a big volt drop.

 

[Jev88]

I suggest you unscrew that black cover to get easy access to terminals and carefully use a multimeter. You will find a connection with engine on (12+ volts) and engine off (zero).
Then you can start looking for a potential fuse or relay blown? My 1999 vehicle has a fuse right off the 12volt supply of the engine bay battery for the fridge.

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[autorouter]

Maybe I'm wrong, but I think the black box has nothing to do with it. I think it's the gas igniter module.

The installation instructions say the 12V power to the fridge heating element must be a separate wire going all the way back to the battery, with its own fuse, probably 20A. It is separate from the 12V supply that powers the control board.

The two heater elements are inside a metal can, filled with insulation, two wires per element. Be careful, one of the elements is mains 240 volts. This can is on the right, above the gas flame.

 

[Jev88]

Maybe I'm wrong, but I think the black box has nothing to do with it. I think it's the gas igniter module.

The installation instructions say the 12V power to the fridge heating element must be a separate wire going all the way back to the battery, with its own fuse, probably 20A. It is separate from the 12V supply that powers the control board.

The two heater elements are inside a metal can, filled with insulation, two wires per element. Be careful, one of the elements is mains 240 volts. This can is on the right, above the gas flame.

Yes, I think you are right - it is the spark generator. Just saw the 12V symbols on it and thought a good place to start to trace the 12v power?

 

[Cliffdale]

I don’t know if this is useful. Taken from the installation manual.

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[autorouter]

Maybe I'm wrong, but I think the black box has nothing to do with it. I think it's the gas igniter module.

Yup, wrong again . It's the gas igniter module, but it looks like it's also the connector block for all the other wires.
The orange wire is the D+ signal wire. It should go to +12V when the engine is running, and drop down to about zero when the engine is stopped. That's how the fridge control board knows the engine state. It doesn't provide any power, it's just a signal wire.

The thick red and white wires, which change to red and brown at the connector, are the 12V power wires that supply the 12V heater element. They should behave like the D+ wire, and go to 12V when the engine is on, and back to zero when it's stopped (if the fridge power selector is on Auto or 12V). If that's what they do, but still no fridge cooling, then probably the 12V element has blown.

If no 12V on the red wire, maybe the fuse has blown, or the fridge relay is not working. There should be a D+ signal to the coil of the relay. The relay will probably be either near the engine or near the 12V distribution fuse box.

 

[pagey]

Excellent thanks for the replies I will have a test with a meter tomorrow I have checked the 20 amp fuse and that is OK

 

[Spanner]

Have you inspected the connections within the white plug and socket, ours suffered from a poor connection as you can see in the photo

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[Andy1954]

Ours was a poor connection as above next to the engine battery

 

[pagey]

Thanks guys I can't work on it at the moment as my exhaust is pointing at the habitation door of the van next door on the aire

 

[autorouter]

Ours was a poor connection as above next to the engine battery

The current spec for this type of push-on connector is about 16 amps. Powering a fridge heater element is working right at its limit, so if it's not perfect it will start to heat up. The heat degrades it and it just gets hotter until it fails.

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[pagey]

Hi back home now and looking at my fridge in the photo the red/brown is live all the time with ign or panel switched off the 2 amp fuse which controls d1 is OK main fuse by the engine battery is OK so I don't know how the fridge is controlled by the main battery / engine any ideas where I should next thanks

 

[MisterB]

if its working on gas and ehu, surely its just the 12v heating element that has gone? i would replace that as a first option. i recently replaced a 240v heating element following the advice on earlier posts. took longer to get the fridge out than it did to replace the element.

 

[pagey]

Can see what you are saying but I don't think the element is getting any power and I don't know where to check

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[MisterB]

Can see what you are saying but I don't think the element is getting any power and I don't know where to check

if you read your post again, you will see it doesnt make sense, you only THINK it isnt getting any power, why? perhaps its because it isnt working because its faulty .... why would a 12v supply suddenly stop working, when its been absolutely fine before? if you cant see any obvious shorts/faults in the wiring then just replace the element - theyre not that expensive and it would prob have been quicker to do so than trying to trace if you have power or not.

as you have checked with your engine running and its not running the fridge, some fridges only work on 12v when the engine is running, i would just replace the element personally.

 

[pagey]

I now know now it is not working I don't know if it has ever worked on 12v checked with thermometer this van is only 2.5 years old all I am trying to do is check the 12v supply to the element

 

[MisterB]

is it covered under warranty then? dont replace or repair if it is !!

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[pagey]

is it covered under warranty then? dont replace or repair if it is !!

No only a 1 year warranty

 

[MisterB]

in that case i would still think about replacing it as a first option, even though you dont know if it has ever worked, though i can see why you would want to check for a supply if its only 2 1/2 years old

 

[Shrimp]

Our fridge did suddenly just stop on EHU and hubby took it out and replaced the heating element on the 240v.
but just a thought the fridges always work best on Gas, and when ours is on EHU I have to alter the temp so it runs colder-on EHU I have the temp set at 5 and on Gas I set it to about 3-4.

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[pagey]

in that case i would still think about replacing it as a first option, even though you dont know if it has ever worked, though i can see why you would want to check for a supply if its only 2 1/2 years old

yes i have no problem changing the element except this is a fair size fridge freezer to pull out i am not understanding where it gets its signal from

 

[jockaneezer]

Have you checked the fridge's connections at your van's distribution box (Electrobloc or whatever's fitted)? I had a similar 12 volt cooling issue and it was the spade connector on my Reich Xbox that had failed, just like Spanner posted, but mine burnt out the track on the pcb too. Think it cost about £300 to get repaired at Apuljak Engineering.

 

[pagey]

All connections ok

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[WillH]

When my van was new I had the same problem, no cooling on 12v when engine running. Problem was the controller, required replacement. Technician said he had seen a few. This was 2008.

 

[autorouter]

Can you find the wires going to the 12V heater element, and disconnect them? You could use a multimeter to measure the resistance of the element. It should be about 0.7 ohms.

If it's defective, it will probably be either open or short. Open will show up as 'Overload' or OVL on the display when you measure it. Short will show up as less than 0.7 ohms.

Unfortunately at 0.7 ohms it is very near the lower limit of accurate measurement for cheap multimeters. But you don't want an accurate measurement, you just want to know if it's shorted or not. Note that to get a sensible reading, you need to disconnect at least one of the element leads.

The resistance of the test leads and probes is normally about 0.3 ohms. Touch the probes together and measure the resistance of the probes. If your meter doesn't have a 'Zero' button, you will have to mentally subtract this values from the value you measure.

 

[autorouter]

The heater elements are located by the tube that rises up above the gas flame. There is usually a 'can' containing rockwool-type insulation round them. There will be 2 wires for each element, ie 2 for 240V element, 2 for 12V element. If you trace the wires back to the connections, you can use the meter to see if the controller is trying to send 12V to the element. I there's 12V at the connections, but there's no cooling, then almost certainly the element needs replacing.

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[pagey]

what i dont understand here is that the thick white/red wires attached to fridge are live and the voltage is varying as the sun goes onto the solar panel . the engine is not running and the 12v habitation is not switched on

 

[autorouter]

Not sure I understand that either. On my MH, turning off the habitation switch does not turn off the fridge, step and frost protection valve. The fridge can still run off EHU, gas, or (when the engine is running) 12V.

 

[pagey]

hi guys me again as already stated the red/white wires are live 12v from the leisure battery so i am assuming that the 12 volt element is broken or it is not getting a signal from d1 i think it is the small orange wire if so now here is the question how do i test it tia

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