Club 80-90 Forums

I'm puzzled by a problem with the Electrolux RM212 3-way fridge in my 1990 Autosleeper, wonder if anyone else can shed some light for me please?

It's always worked fine on gas, 12V and 240V hookup. Until now, when only the gas works (it gets cold as normal)

I know 12V is getting to the gas ignitor from the battery, as that works fine.

Also when the engine is running and I switch the selector to "battery" on the fridge, the Zig unit LED lights up to show the fridge is getting 12V.

So far so usual.

But the fridge only cools when using gas.

I've checked it's getting power (checked the trip/fuse) from the 240V hookup and that looks fine.

Taking the fridge out to get at the top and problem-solve the wiring looks like a tricky job, so I'm trying to work out the possibilities first.

The 12V and 240v use different heater elements, so I assume they would be unlikely to fail at the same time.

Could there be a common earth problem maybe? The Zig unit shows the 12V switching on, but maybe there's another common earth not working? I've read the circuit diagram on this forum and the 12v shouldn't share an earth with the 240V, but I suppose it's possible.

Or is there a fuse for the 12V somewhere, even thought the Zig light illuminates as usual when the 12V is switched on with engine running? OTOH that shouldn't affect the 240V operation?

The ONLY things that happened to the van before I noticed the fridge stopping working electrically were:
1- garage had the dash out to replace the blower motor.
2 - I used the van to jump-start our car

Could either of those have disturbed anything relevant?

Any ideas or advice welcome please

How long are you giving it before you decide it's not cooling?
My fridge takes a few hours to get cold on ehu, and on 12V it just really maintains the pre-cooled fridge temperature, it doesn't do much real cooling, not like on gas or 240V.
When I first got the van, I was convinced that the fridge wasn't working, but I left it on hook up over night, and in the morning there was a healthy layer of frost in the ice compartment.

Thanks A1, 24+ hours on 240V shows no cooling at all. A few hours driving from it starting frozen (gas) saw it defrost whilst switched to 12V, although the zig light showed it running.

I have a Rm212F. All three systems are independent but use the same insulated chimney stack to heat the pipe work. On mine, the gas doesn't need 12v to light the gas - it uses a piezo crystal. I measured my heating elements the other day: the 240v element has a resistance of 492 ohms and the 12v was 0.01 ohms.
I know you don't want to pull the fridge out but at least this gives you some values to compare against.

If yours is the same as mine then the chance of two independent heating systems failing simultaneously is negligible. I'd look at something external. The zig unit? Although I don't know which type you have.

Thanks Bubble Meister, I agree about the chances of 2 heaters failing together being slim.
Thanks too for those measurements, might come in very handy if I do relent and pull the fridge out.
Not sure what model the zig unit is, will have a look. Actually, I'm not even sure what the Zig unit does with regards to the 240 supply to the fridge, is it even involved? Mains power seems to go straight from the hook up to the main trip (the trip fuses are on a separate panel), via a 5a trip circuit to the fridge. The zig has no mains switches, just a 12v supply switch, a water pump switch (for the tap), a water tank level meter, battery condition red/green LED (no leisure battery, it's for the main battery), and a fridge light for when the fridge is running at 12V.
I think you are right about it being something external, I just can't think what, or where to look.

Bubble Meister wrote:the 240v element has a resistance of 492 ohms and the 12v was 0.01 ohms.

Something wrong there, I think. The 240V figure looks about right but the 12V is much too low. I think about 1.0 to 1.4 ohms would be about right.
The 0.01 ohms figure gives a current of 1200Amps (ish)!