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Fridge Coolant System Prob


pilchard

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My 22 year-old 3-way fridge, an absorption-type fridge... Electrolux RM4213S, is playing up and has not been cooling on mains or gas and performing pretty poorly on 12volt... despite heat coming from the flue on all 3 sources.

I took it out yesterday and left it upside-down overnight... cleaning out the cup jet at the same time because the gas flame was a little weak. Re-installed it today, tried it on gas (with a good flame) and a couple of hours later it was actually warmer inside the fridge than outside. The same happened when I ran it on 240volts. Have not tried 12volt, but the poor/no performance with hot flue on all sources leads me to the only possible deduction that it is a coolant system fault.

I've done this turning upside-down trick a year or so back with excellent results, although that time I didn't leave it up-side down overnight... just a few moment.

Are there any variations on this wacky technique I can try?

Is re-gassing a feasible option?

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Absorbtion fridges typically use ammonia and water as the means of extracting heat from within the fridge and over time the ammonia crystallises in the tube above the heater and renders the fridge useless. 

Unfortunately if this is the case then the fridge requires a complete new heat exchanger 'mechanism' as the crystallised ammonia cannot be reversed.

More is explaine on Wiki... https://en.wikipedia.org/wiki/Absorption_refrigerator

image.thumb.png.b7089de4326a980c778ab4c23ae6c4a7.png

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Thanks for the Wiki link Keithl. Fully understanding the chemical and physical properties that these systems use is a little beyond me, and I was really looking for some advice on various tricks that can be applied to coax this fridge back into action and so allow me time to track down a replacement. I've seen a video where the guy turns the fridge clockwise (looking from the back) onto its head for a day and hits the tubes gently with a hammer every couple of hours. I'd turned my fridge clockwise....

Another wrinkle I'm also currently trying is running it on 240volt and gas at the same time in the hope that it might turbo charge the liquids and gases into moving sufficiently to dislodge any blockage. Will try the hammer trick if this fails.

I know this'll all sound crazy to some, but desperate situations require desperate remedies.

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14 hours ago, Keithl said:

Absorbtion fridges typically use ammonia and water as the means of extracting heat from within the fridge and over time the ammonia crystallises in the tube above the heater and renders the fridge useless. 

Unfortunately if this is the case then the fridge requires a complete new heat exchanger 'mechanism' as the crystallised ammonia cannot be reversed.

More is explaine on Wiki... https://en.wikipedia.org/wiki/Absorption_refrigerator

image.thumb.png.b7089de4326a980c778ab4c23ae6c4a7.png

The question then is, can the complete meat exchange module (including refrigerant) actually be changed, and at what cost? 

At 22 years old the fridge has fully earned its keep so, with the recommended Dometic RM5310 the (near enough like for like) replacement costing in the region of £1,000 retail, the further question seems to be how much is it worth spending on repairing/replacing a 22 year old fridge in a (presumed) 22 year old motorhome?

Part of the answer to that, affordability apart, must surely also concern how long the owner expects to continue motorhoming, and whether he may be considering (fridge difficulties aside) changing the van in the relatively near future.

It's a sort of loss - reward question.  Whether it is better to bite the big bullet and change the whole caboodle sooner rather than later, so gaining (extent depending on what replaces it) in addition lower exhaust emissions (and so reduced hassle on that score) plus gaining a newer, more reliable, vehicle overall.

One further issue is the continuing reliability of the existing fridge if "tricks" do bring it back to life.  How much impact would failure of the fridge have if it occurred in mid trip?  It has now failed, apparently for the same reason, twice.  The failure process is well explained by Keith.  My understanding is that the crystallisation of the ammonia is not reliably reversible, leaving the system permanently prone to repeat instances, with "jiggling" the fridge around achieving no more than loosening the individual crystals at the point of blockage without removing them from circulation or converting them back to their previously liquid state.  Its that old issue of repeatedly doing the same thing while expecting different results.

Hard decisions, I'm afraid.  😞

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Just on this, it seems the cooling module may be available as a spare (or series of) parts.

See Chris's "Dometic RMD8555 not working gas or electric but no warning messages" post of 27 June.

The part was described as the "cooling tower", though it seems it may also be known as a "cooling generator".  "Leisureshopdirect" is advertising one, albeit for a different fridge, at £650, but that is parts only.

Due to the the nature of the refrigerant, this is a job for a certificated refrigeration engineer (so a definite DIY no-no) and it appears that considerable assembly work is involved plus complete re-gassing.

Best answer on cost would involve getting a Dometic fridge engineer to quote but, assuming the above is a reliable parts cost guide, whether it would be worthwhile compared with the cost of a complete new fridge swap, seems to me questionable.

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Hi

Repairing, really isn't cost effective on a 22 YO fridge, much more economical to change for a new one if you are going to carry on with your motorhome or try turning over "trick" now and again and tapping etc' But then it still could let you down anywhere (as Brian points out)  and sometimes it may be so far gone it may not work. If it works some are happy enough to live with this method every now and again , it It's your decision. The main thing is to go out and enjoy 

Regards 

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Success! 

Using the two links below as a guide... one that mentions anticlockwise rotation, and the other that recommends hitting it with a hammer... I hybridised them and worked out my own plan.

I rotated it anti-clockwise onto it's head, spent a minute or so tapping with a 6 ounce hammer all the coolant pipework, rotated anticlockwise on it's side and repeated, then the same right way up, then over again and repeated, rotating anti-clockwise at all times. I gave it a few shakes both upside-down and right way up, gave it a half-hour rest... then re-installed it.

It now freezes like a dream in all 3 modes.... down to -16c in the ice-box, which will do me fine.

Thanks for all the very much appreciated advice though, but with a special thanks to Colin M50 for the Ebay link to the bargain priced SMAD fridges.

http://hymers700.blogspot.com/2019/10/turning-fridges-upside-down-truth-about.html

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