# Fridge not working on 12 volt



## fofeg101 (Jul 17, 2011)

My Electrolux RM 4200 fridge will not work on 12 volt running off the vehicle battery, it works fine on Gas and Mains 240 volt, so the absorption side of things is circulating OK. I took out the 12 volt element and put it across a 12 volt car battery in my garage, it gets very hot so that isn't the problem. I connected up the element to the fridge leaving the heater probe exposed, started up the engine and switched on the 12 volt switch on the fridge, the indicator bulb lights up and checking with my multimeter I'm getting 12 volt to the probe...but it doesn't even get slightly warm. The cable supply seems to be heavy enough so I can't see that being the problem. It could be a bad earth or connection somewhere, I suppose. I've only tried it with the engine ticking over, could it be it needs the engine revving harder to get juice to the element....I'm clutching at straws, as anyone got any ideas please? I'll have another go at it tomorrow after I've slept on it.


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## Deleted member 207 (Jul 17, 2011)

Try removing and reseating the 12V spade connectors in turn. They can often form enough corrosion to cause a "dry" connection. 

Depending on how your fridge is wired up will depend on the next steps - does the vehicle have a 12V controller which only allows 12V to the fridge when the engine is running (some do some dont)?


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## Tony Lee (Jul 18, 2011)

Some fridges have TWO 12V supplies to the fridge. One is just for the control circuit and will come from the habitation battery.
The other comes from the car alternator via some sort of sensing circuit that only connects the element when the alternator is producing output. These two supplies are not connected in any way.

Check both these circuits when the engine has been running for a couple of minutes at high idle.

If the heavy 12V supply is showing zero volts then you need to check for blown fuses or a relay or electronics problem in the part of the power management system that supplies the fridge with 12V for the heater.


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## fofeg101 (Jul 19, 2011)

Thanks Roger & Tony Lee, Here's an update on my progress. Today I called into a local Caravan Fitter, but it was like "The Blind leading the Blind", he was no more familiar with the problem than I am. Anyway, I got a copy of the Haynes "The Motorcaravan Manual", and found out I have to locate a relay, a job for tomorrow,when I'm sober. I think there's an anomaly in the text in that book, on Page 117, it says.. "If a refrigerator doesn't work on 12 volt"..."Ensure the fridge's selection switch is set to 230V operation", on my fridge there's no co-relation between the 230V and the 12V, I've got a feeling it's a "typo" 230V should read 12V.


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## Deleted member 207 (Jul 19, 2011)

Try the Electrolux/Dometic manual at http://gasrefrigeration.net/dom_techdata/36044804.PDF its the US version so replace 110V with 240V, but essentially the same animal.


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## fofeg101 (Jul 20, 2011)

Roger, Thanks for the info., it doesn't refer specifically to the RM4200 but it mentions that relay, I think that's where my fault is, around that relay. I've checked, stripped and cleaned all connections around the fridge end and under the vehicle bonnet. In a cupboard behind the gas heater there's a whole bunch of electrics for the habitation area, including a board with relays on...that's the next place to look. I can't look today, the wife tells me I'm going to be "busy". It's a shame that the Motorhome manufacturers don't give a wiring diagram with the van, mines a Herald, no longer existence I believe.


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## Tony Lee (Jul 20, 2011)

Before you go ripping everything to pieces there might be one thing to check before assuming it is aa relay.

Assuming you have a multimeter, measuree the house battery voltage without the engine running and then after the engine has been high-idling for a few minutes, Assuming your vehicle does have charging from the engine, the voltage of the house batteries should rise. If not, then the control signal from the engine ignition circuit may have a blown fuse. On mine, they ficked up a feed from the brake light switch and that fuse had blown so the habitation control system wasn't getting the signal to start charging the battery or supply the fridge.

Your system will be entirely different but you need to keep an open mind as to what the root cause might be.


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## fofeg101 (Jul 24, 2011)

I just found a couple of very useful posts on the net.

1) Clive`s

2) 3 way fridge

Plus, I just bought a used relay off eBay, £2.95 inc, postage.

Tomorrow I'm going to make sure I've located all of those fuses and bell out the wiring from the fridge back to the relay.

Watch this space.

 BTW, that "caravan fitter" I talked to said I would have to run the van for 100 miles for it to get cold on 12 volt..???? In the next breath he said the element should glow red hot....??? Am I asking too much for the fridge to get cold on 12 volt?


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## Tony Lee (Jul 24, 2011)

> ??? Am I asking too much for the fridge to get cold on 12 volt?



Most fridges of this type struggle to even maintain temperature on 12V let alone cool down a heap of hot stuff. Usual thing is to run the fridge on 240V or gas for 24 hours before the trip and only load it up with pre-cooled food.

Most 3-way fridges do not have a thermostat on the 12V circuit so that gives you some idea of how effective it is likely to be. Another problem is that the wiring is often very marginal in capacity so the voltage drop is too high - and since the heat generated by the element is proportional to the square of the voltage, a one-volt loss can mean a big reduction in heat and therefore in cooling.

(The element would be red hot on the inside of the element cartridge, but of course not red-hot on the outside. Way too hot to handle though since it has to produce close to the same amount of heat as the flame)


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## Bridb (Jul 25, 2011)

*thetford fridge freezer not working on gas*

Hi, we have a thetford fridge freezer 2005. it has had about 6 full weeks use yearly. The gas stopped working and a dealer in Ireland replaced the "panal" at the back. It has worked for a total of 16 nights and is gone again. I can hear it clicking, trying to ignite but then the red light comes on. Its working fine on battery and electric. Any advice? Brid


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## Tony Lee (Jul 26, 2011)

Bridb said:


> Hi, we have a thetford fridge freezer 2005. it has had about 6 full weeks use yearly. The gas stopped working and a dealer in Ireland replaced the "panal" at the back. It has worked for a total of 16 nights and is gone again. I can hear it clicking, trying to ignite but then the red light comes on. Its working fine on battery and electric. Any advice? Brid



That probably indicates the ignitor is working, so the panel itself may be OK - but there might be a fault with either the gas solenoid valve or in the wiring to the valve. This might be either in the 12V supply between the panel and the solenoid valve, or just as likely, a poor connection in the ground lead to the valve solenoid coil.

Easy to check with a multimeter.

Sequence of events is solenoid valve opens with a muted clunk and at the same time the igniter starts the spark going. Then provided the flame starts, the ignitor stops and the valve stays energised. If the igniter fails to light the flame, the electronics assumes a fault and de-energises the valve and shuts the spark off and signals a fault on the front panel.
Of course the system in your fridge may be quite different so the above is just general info that may help.


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## fofeg101 (Jul 26, 2011)

I've put my "not working on 12 volt" problem on the back burner, I'm busy elsewhere for awhile. When I get around to having another pop at it I'll report back here, hopefully my experience will help others. I can run the fridge on gas, just turn it off before I pull in for fuel.


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## fofeg101 (Aug 11, 2011)

Problem solved, I changed the relay and 12v element gets red hot. I'm taking the van for a 100+ mile run tomorrow so it'll give it the final test.


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## fofeg101 (Aug 13, 2011)

Result. After 100+ miler on 12v, fridge working fine from warm!!. The caravan fitter who said it would only back up from cold was wrong.


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## fairytooth (Aug 13, 2011)

Bridb said:


> Hi, we have a thetford fridge freezer 2005. it has had about 6 full weeks use yearly. The gas stopped working and a dealer in Ireland replaced the "panal" at the back. It has worked for a total of 16 nights and is gone again. I can hear it clicking, trying to ignite but then the red light comes on. Its working fine on battery and electric. Any advice? Brid


 
2 things occur to me:

Obviously make sure your gas supply is good and no leaks, etc.

Also we have the 3-way Dometic with auto setting BUT if gas is switched off (eg for Eurotunnel) we have to set the dial back to OFF before the gas will restart.  Leaving it on the GAS setting just doesn't get it restarted for some reason.


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## runnach (Aug 13, 2011)

fairytooth said:


> 2 things occur to me:
> 
> Obviously make sure your gas supply is good and no leaks, etc.
> 
> Also we have the 3-way Dometic with auto setting BUT if gas is switched off (eg for Eurotunnel) we have to set the dial back to OFF before the gas will restart.  Leaving it on the GAS setting just doesn't get it restarted for some reason.



I think you have answered your own question in a sense;

The system thinks there is a gas fault i;e loss of pressure and so has closed down, hence the reset required.

How many of us have changed a gas bottle for a full one only to find that nowt works? then in a flash of inspiration we remember we didnt press the little under pressure shut off valve on the regulator ? you know the one hidden away underneath the regulator where you cant see it.

I think your fridge is working on the same principal therefore normal behaviour and actually the system is doing its job. 

Channa


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## fairytooth (Aug 14, 2011)

Quite right, thanks for that.


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## fofeg101 (Aug 14, 2011)

fairytooth said:


> 2 things occur to me:
> 
> Obviously make sure your gas supply is good and no leaks, etc.
> 
> Also we have the 3-way Dometic with auto setting BUT if gas is switched off (eg for Eurotunnel) we have to set the dial back to OFF before the gas will restart.  Leaving it on the GAS setting just doesn't get it restarted for some reason.


My fridge employs old technology, the gas has to be light manually, you just need two strong thumbs, one for pushing in the knob to hold in the thermo- electric flame failure device and one to keep pushing the knob which activates the piezo ignitor, it's simple, I like it.


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