A/S Trident Fridge not working on 240v

Hi all,

Bit of a conundrum...

The fridge on our 1993 Trident seems to work ok on 12v and Gas, but doesn't seem to work on 240v. The 240v connection seems to be working, as the plug works, and the RCCD test button works, and there's no obvious issue with the MCBs.

There's no fuse in the Zig for the fridge 240v, so I don't thinks it can be that.

So, I think it can only be one of the following, but would appreciate any further thoughts:

1. Dodgy wiring;
2. Dodgy fridge switch, with the 'plug' terminal not working; or
3. Dodgy 5A MCB, although not sure what the problem could be with this (I wonder can this just trip/go like a normal fuse?).

Any comments/advice welcome.

Thanks all.

I'd agree with BobK - if you can trace the mains to the switch on the fridge and it's good through the switch then it's almost certainly the element.

Having said that, of all the problems of this type that I have looked at, by the far the most were wiring issues, with element failures ~fairly~ rare...

So...I've done some investigation and the element gets hot when out of the fridge, so I think that scuppers that idea (I think). This seems to tally with mojo's thoughts that element failures are pretty rare.

Short of getting a fridge engineer involved, which I'm reluctant to do, does anybody have any further thoughts?

Or, it's a new fridge...:-(

Thanks.

Perhaps I'm being too simplistic, but that begs the question: does it get hot when it's back in the fridge, in the van?

It was still connected, in the van, when I tested it. I just removed it from it's holder.

C.J.Mylchreest wrote:Or, it's a new fridge...:-(

Can't think of a reason why you'd need a new fridge.

It needs a heat source to work and it works with both gas and 12V so it can really only be the 240V element not providing heat for some reason. A few measurements should soon pinpoint the cause but whether or not you need an engineer depends on confident you feel working on 240V.  If you're at all unsure paying an engineer to look at it for you is money well spent.

There are several possible causes that come to mind, the most likely being that the thermostat cuts out before the fridge gets cold. Much less likely but still possible  causes are the element failing as it gets hot or a connection problem. It's not unknown for connections to make and break as you move the wires about (which you will have done when you removed the element).

I think the most comprehensive initial test is to measure the voltage across the element and the current the fridge takes at the same time. If the voltage on the element disappears it has to be the thermostat or wiring. If the voltage stays correct and the current falls to zero it has to be the element.

Brod.

Brod,

Thanks for the reply, and the confidence! Having done a few more tests this afternoon, here's what I know:

- it only seems the freezer cooling element (the thick black tube) gets cold under 12v, with the one in the main fridge (with the silver fins around it) never seeming to get cold to touch. In other words, under gas and 240v nothing seems to get cold, not even the freezer compartment.
- the igniter and gas flow appear ok, as the auto-igniter works until it is lit as it should.
- after putting the fridge back together after testing the element, nothing changed in terms of performance.

What you say about the thermostat might be about right, as I know that when working under 12v there is no temperature regulation, it is just either on or off. Not sure how I test this, but I suspect it is testing the voltage at both ends.

So, not being confident with 240v, my options are I guess to call out a fridge engineer (assuming they'll work on a 23 year old unit), and pay the probable £50-100 for the pleasure, running the risk the fridge is knackered somewhere, or maybe consider a sparky instead.

One thing complicating matters is there's an rm212 on eBay at the moment for around £100 which is apparently in perfect working order! Obviously a risk too, but maybe worth a shot.

Any further thoughts much appreciated!

Thanks all. CJM.

One further thing that may be relevant: Is it sitting dead level while you are testing it with the van stationary? That type of fridge is very sensitive to level, and it only has to be out by a few degrees and typically it will stop functioning.

The other thing is that the design of absorption fridges is such that they can be very slow to get going. The one on my last van (which I owned for 10 years) was pathetically slow from a warm start. For the first 2 hours it would do almost nothing, and then the internal circulation would get going, and if left running on 240V overnight it would then really get moving. I think that this is a fundamental characteristic of the design - it is quite a complicated circuit, and the whole thing needs to run on internal convection (obviously, as there is no pump) which can take quite a while to get established.

BTW, I would not bother calling out a refrigeration engineer - if the elements and gas burner are working as they should, there are no other serviceable parts. The only remedy from there is to take off the whole refrigerant assembly and replace it with a new one (if you can find one).

Thanks again mojo, very much apreciated.

Sounds like I need to do another final proper test, having the 240v connected overnight (on a level surface, currently it is definitely sloping!), and see whee we are. I do note that when switching from 12v to 240v or gas, the freezer compartment actully defrosts, so it isn't often from warm.

A couple of quick further questions:

1. Is it possible that the element gets warm, but not warm enough to make the fridge function?
2. Given it is the 240v and gas which seem tempramental, and these are controlled by the thermostat/selector (and the 12v isn't) could it be this that is faulty?

I may well buy the ebay fridge anyway, then I'll have loads of parts!!

Cheers.

Hi  

C.J.Mylchreest wrote:Given it is the 240v and gas which seem tempramental, and these are controlled by the thermostat/selector (and the 12v isn't) could it be this that is faulty?

Err I thought it was OK on gas.

C.J.Mylchreest wrote:The fridge on our 1993 Trident seems to work ok on 12v and Gas,

There are thermostats on gas and 240V (or whatever they call the gas version) but I think they're totally separate units.  If you search the forum you'll find there are other reasons why it may not be efficient on gas, most to do with the burner.

It is possible for the element for the element to run cool but that would mean high resistance on one or more of the connectors and that normally shows because the connectors get hot or burn.  I don't think it's very likely in this case. The problem is that there are so many possibilities and if you can't do appropriate measurements you can waste a lot of time (and possibly money) "chasing your own tail".

It sounds to me as if the fridge needs a good service.  It might be worth  finding a service engineer in your area and asking for feasibility and approximate cost of a repair and service. After all asking the question doesn't cost anything and sometimes getting a professional in can actually save you money.

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Replacing the fridge with a second hand unit is certainly an option but there is the risk of ending up out of pocket with two duff fridges . If you do fit a second hand unit you may well want to get it checked and serviced anyway so that's another cost to consider.

Brod

Yes, I thought gas worked OK, but it didn't seem great at the weekend, in that when I switched from 12v to Gas, the freezer compartment defrosted, which raises suspicuions!

Thanks for the advice regards approved servicing, I will give them a call.

I had already realised I was chasing my tail a little, and have contacted these guys for a quote:

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Thanks again...I'll keep you updated!

C.J.Mylchreest wrote:currently it is definitely sloping!

That will almost certainly be your problem. Absorption fridges seem to work very well on 12V when being shaken about on the move, but if you park on a slope it is likely to stop them dead. Test it on the level and take it from there.

I am going to run a test on the 240v overnight tonighht, and see how we go. Cheers.

So...first test completed. I levelled the van outside the house (looks a bit gash on bricks and wood!), and then ran it on 240v overnight.

After about 3 hours last night, there was some sign of cooling (condensation in the freezer), and the back of the fridge was nice and toasty, presumably indicating the element was working.

Checking this morning, there was no cooling at all, and I may as well just have left it unplugged?! The back fo the fridge was luke warm, but cooler than last night.

Second check today is to run it on gas this morning and check at lunch.

Keep you posted...

Now you've said it doesn't work that well on gas either, then I think it's time to remove the fridge and stand it upside down overnight, then turn the right way up and repeat. This gets the gas circulating throughout the pipework. Refit and try gas and electric again. This trick has been around for years often with good results.

Thanks Paul, I might just try that - it would be great if it was an easy fix like that!!

Yep - i've heard that the 'turn it upsidedown' is often very successful. Hope it works!

Steve

Perhaps especially so given the 12 months before I bought it, it only covered 1 mile!

Right, further update. The gas system seems to work, as the fridge and freezer are lovely and cold at lunch time today!

I am strongly suspecting it is now the 240v element which is a little dicky...

Ok, rapidly losing patience now!

Took out the fridge and left it overnight upended, in fact did it twice. Now back in and gas working ok, but absolutely no refrigeration after 2 hours!

I have levelled the van but notice that the freezer shelf is very wonky (so not level). I can't think a wonky shelf/coolant tube would stop it working, but maybe (if the refrigerant was getting stuck or something?).

We're going to France in about 4 weeks so getting to the point where I will be considering a new, or second hand, unit.

Unless any further genius thought!!

Thanks.

I think you need to leave it running for more than 2 hours. Take a look online at a diagram of how an absorption fridge works and you will see that it is a weird and complicated system. I've heard said several times before that if you invert them they can take quite a while to re-establish the internal coolant flow.

Cheers mojo. Further update...ran it on 12v and it started cooling, then switched to gas and it continued cooling as far as I can tell (icy freezer box).

Will try on 240v tomorrow.

Phew....!!

The 230V element should be reasonably easy to replace, if you can find the correct part.

It's usually a curved steel tube which slides up inside the insulated heat exchange module.

Similar to this one:

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Thanks, yes I have one on the kitchen table which I've bought to try. If you read through the thread you'll see that the fridge is seemingly more temperamental than just failing on 240v, although it's all a bit random!

Currently trying the fridge after taking it out and rotating it!

Thanks for the reply.