Onboard fridge stopped working - any ideas?

[owen-cox]

That is simply not correct. It is perfectly possible to retrofit R134a. R134a uses PAG oil, not ester. R12 mineral oil can be replaced with POE oil (which is an ester oil) and will mix with small amounts of mineral oil. I've done several retrofits and every single one has worked perfectly well.



A small amount of polyol oil with dye in it finds leaks easily.

I worked with several of the large marine refrigeration companies (dometic, condaria, isoltherm, frigoboat etc) as an agent and I was advised by all as well as OEM compressor manufacturers manuals not to mix any amount of mineral and polyolester oils together. R134a will not mix with mineral oil and will not allow the oil to move around the system correctly. How could you be sure you got all the oil out of the compressor?
I too have done replacements of refrigerants but as the outcome is not 100% certain I would not recommend it on a system that has been obsolete for 20 years.

 

[PaulRainbow]

I worked with several of the large marine refrigeration companies (dometic, condaria, isoltherm, frigoboat etc) as an agent and I was advised by all as well as OEM compressor manufacturers manuals not to mix any amount of mineral and polyolester oils together. R134a will not mix with mineral oil and will not allow the oil to move around the system correctly. How could you be sure you got all the oil out of the compressor?
I too have done replacements of refrigerants but as the outcome is not 100% certain I would not recommend it on a system that has been obsolete for 20 years.

You don't have to be sure you got all of the mineral oil out of the system, although a lengthy evacuation should remove the vast majority. The correct POE oil will mix with mineral oil.

You may be correct that the system is best replaced, but i don't think it'd hurt to get someone to take a quick look, provided he doesn't charge a fortune. Maybe someone has defrosted it with a knife lol

 

[superheat6k]

You don't have to be sure you got all of the mineral oil out of the system, although a lengthy evacuation should remove the vast majority. The correct POE oil will mix with mineral oil.

You may be correct that the system is best replaced, but i don't think it'd hurt to get someone to take a quick look, provided he doesn't charge a fortune. Maybe someone has defrosted it with a knife lol

So you want a low cost job, with a lengthy evacuation. This presumably follows on from a proper leak pressure test, and assumes the leak will be found. The issue here is that the skilled fridge engineer who does this task on a tiny 30 year old fridge will cost the same as that same engineer assigned to a large and complex supermarket refrigeration system.

Any fridge firm worth their salt will be looking at similar labour charges to a medium size established garage business, plus travel costs, so expect ~ £45 hour, with as mentioned in another post a requirement to cover all the engineers time assigned, not just at the boat itself.

R134a requires the old mineral old removed first, and this is not viable (to do properly) by simply banging in POE oil and hoping. HFC refrigerants such as R134a do not work properly with > 5% back contamination of mineral within the POE oil.

If the leak is found say after 2 hours spent dismantling and pressure testing plus similar in travel and prep costs, thats half a day at £45 of £180 all chargeable and still the OP has to buy a new fridge. Even if the work is successful the Op has by then laid out by then ~ £300 and still has no guarantee, unless the engineer doing the work is commercially naive and offers one on 30 year old kit (some do !).

Our firm declines involvement with this sort of kit as it is a money pit for all concerned. If this were my unit I could do these repairs myself as I have the equipment and would regard it as part of any other maintenance or repair task on my boat, although I would not want to spend anything at all on this specific kit. However, I would not do this for others except close friends as a favour. Even then I would decline to charge R12 into this kit and I simply do not agree that the R134a option will offer any form of long term resolve, but might get then another season I suppose.

 

[PaulRainbow]

Last boat i did was R12 to R134a, cost the owner peanuts and is till working after 4 years.

Not everyone charges £45 an hour and not every job is a big one. Just because your company wouldn't touch it doesn't mean a marina with the kit wouldn't take a quick look. If it was someone in my marina i'd be happy to take a look for a drink. I happen to know i'm not the only one in his particular marina who'd do the same.

Simple fact is, thousands of systems have been retrofitted and work just fine.

 

[rob2]

True, a lot of retrofits are or have worked fine (it's a long time since they switched!). I'm more concerned as to why the refrigerant may have been lost. All fridge compressors at this level have seals which not only fail in themselves, but wear at the shaft so that a replacement seal is usually only a short-term cure. So, if you can find someone to fix it for the price of a few pints, then great - and a bonus if it keeps working all season or more. That's the trouble -it's old and no longer owes you any service, so only worth a small punt to keep it going.

The electric compressors I've looked at have pinched off fill tubes, so access can be tricky, but not impossible bearing in mind you're going to have to evacuate it anyway. My own background (some years ago) was with automotive belt driven compressors - the type that was to be found on every charter boat in the Caribbean running fridges and aircon.

Rob.

 

[Ruffles]

...
I would buy a new system and fit it yourself which will save quite a bit of money and mean you get a fully guaranteed working system that can be repaired in the future if needed.

And a new Danfoss BD35 compressor will use a lot less battery power. I bought a kit years ago. Best thing I ever did.

 

[PaulRainbow]

That's the trouble -it's old and no longer owes you any service, so only worth a small punt to keep it going.

Exactly, just what i was saying.

The electric compressors I've looked at have pinched off fill tubes, so access can be tricky, but not impossible bearing in mind you're going to have to evacuate it anyway.

Remote boat systems on R12 tend to have service ports, in my experience. But it would be simple enough to fit one or just use a line tap, which only costs 5 or 6 quid. If it was knackered take the line tap back off.

 

[superheat6k]

Exactly, just what i was saying.



Remote boat systems on R12 tend to have service ports, in my experience. But it would be simple enough to fit one or just use a line tap, which only costs 5 or 6 quid. If it was knackered take the line tap back off.

And vent the gas presumably. Unbelievable !

Anyway line taps are notoriously unreliable and will cause as many leaks as they repair.

 

[PaulRainbow]

And vent the gas presumably. Unbelievable !

Anyway line taps are notoriously unreliable and will cause as many leaks as they repair.

For a start, it'll almost certainly have a service port, so why does anything get vented ?

Secondly, it's a good bet that it's already leaked all the gas, so nothing to vent, even if you wanted to.

Finally, how will a line tap vent the gas ?

Nothing in what i said even remotely suggests venting gas to atmosphere.

I was working on refrigeration back in the 80's when we did vent R12, because that was how it was done, and fitted countless line taps, don't recall having one leak. In those days we didn't just dump everything, we fixed stuff, guess i've not quite got into the habit of throwing everything away without checking to see what's wring with it.

 

[owen-cox]

It probably has the same problem as my fridge anyway so any gas of whatever type will probably leak out in 5 minutes anyway. As can be seen it's usually the aluminium lacquered pipe that rots away. Mine is of a similar vintage although I believe the plate has been replaced at some point since 1984 when the system was fitted.

 

[owen-cox]

True, a lot of retrofits are or have worked fine (it's a long time since they switched!). I'm more concerned as to why the refrigerant may have been lost. All fridge compressors at this level have seals which not only fail in themselves, but wear at the shaft so that a replacement seal is usually only a short-term cure. So, if you can find someone to fix it for the price of a few pints, then great - and a bonus if it keeps working all season or more. That's the trouble -it's old and no longer owes you any service, so only worth a small punt to keep it going.

The electric compressors I've looked at have pinched off fill tubes, so access can be tricky, but not impossible bearing in mind you're going to have to evacuate it anyway. My own background (some years ago) was with automotive belt driven compressors - the type that was to be found on every charter boat in the Caribbean running fridges and aircon.

Rob.

Engine drive open type compressors have seals but hermetic 12V Dec compressors don't. Indel and Danfoss compressors usually have service ports fitted on boats but Sawafuji compressors as fitted to some fridges usually have crimped over ends. Personally I used to de solder them from the compressor and insert a proper service port because I found that line tap valves are rubbish and nearly always leaked in the long term. I could never give a guarantee if I didn't install a proper valve. What I would do on my own fridge and what I would do for a client are however two completely different things. I built myself a fridge on one of my boats that used a Danfoss compressor that had been completely submerged for a week on a yacht that sank. New electronic unit and it was good as new. Insurance paid for a new one complete for the boat in question and I was told to dispose of the old one... So I did!