Isotherm Fridge

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SteveA

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I have a R12 Isotherm fridge which isn't cooling very well (it is 25yrs old!) and suspect that it needs to be regassed.

Is this something I could have a go at myself or would it need to be vac'd down and then recharged? - has anyone experience of doing this?
 
You cannot recharge with R12, this has been illegal for many years following phase out in the early nineties and the gas not manufactured due to Its very bad effect on the environment. You will not even find any R12 to use anyway. No real alternative is easy on such a small system and the cost of any mod would be higher than a new unit. The pipe sizes and compressor are not compatible, the oil wrong and the evaporator plate not suitable.

Sorry to give you bad news but a new system would be far more efficient anyway.
 
I believe it is possible to get it regassed with a modern equivalent of R12 with no other changes - check for car air-con regassing. This has never been a DIY job!
 
SteveA said:
I have a R12 Isotherm fridge which isn't cooling very well (it is 25yrs old!) and suspect that it needs to be regassed.

Is this something I could have a go at myself or would it need to be vac'd down and then recharged? - has anyone experience of doing this?
Click to expand...

R-12 refrigerant is probably not available for having a go yourself, and for good reason. R-134a is available, but it's not as simple as just recharging with that, as it's not compatible with the oil in your compressor, so that would need to be replaced as well. So you're rapidly approaching the level of difficulty and cost (even if you do it yourself) where it makes more sense to opt for installing a new system (a fairly easy DIY job). Cost depends on the capacity you need, but typically starts around €500.
 
Yngmar said:
R-12 refrigerant is probably not available for having a go yourself, and for good reason. R-134a is available, but it's not as simple as just recharging with that, as it's not compatible with the oil in your compressor, so that would need to be replaced as well. So you're rapidly approaching the level of difficulty and cost (even if you do it yourself) where it makes more sense to opt for installing a new system (a fairly easy DIY job). Cost depends on the capacity you need, but typically starts around €500.
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But there are alternatives to R134 specifically designed to regas systems originally filled with R12
 
Yngmar said:
Which?
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I don't remember the details but Google will find it.

I looked into this in relation to the air con in a 1990 car a few years ago and it was possible without modification. I didn't bother as I don't really understand the logic for having Air con in a convertible :)
 
Isceon (Du Pont) offered their gas MO49 Plus (R437A) for a while as a 'direct replacement' for use in R12 systems. However, because R12 hasn't been used in any new equipment site 1995 and was banned in 1997 (charging into systems) the demand now for a replacement is minute. It remains perfectly legal to operate an old fridge with R12, and this begs the question where has the R12 gone. Sure as light means day if it has leaked and you simply top it up the new gas will go the same way.

So is it time to accept you have had damn good service from your old fridge, and now it is time to send it gracefully to the great refrigerator retirement home in the sky (aka your local scrapyard).

R437A is available from Ebay sellers in Germany, but you will also need to locate the leak and fix it, then pressure test to confirm the leak is fixed, then evacuate it to deep vacuum so a decent vacuum pump is required then finally a manifold to recharge the new gas. Not to mention the experience and to do this properly / legally, at least F Gas Cat 2.

I had to buy a small cylinder of R404A last year and had to send the Ebay supplier concerned a copy of my Cat 1 F Gas, but how strict they are on this I am not sure. Not cheap BTW and all refrigerants are rapidly becoming very very expensive as a direct result of the EU deciding to phase down all Fluorinated refrigerants.
 
I'm going to give a slightly different point of view.

If you are only just now thinking about adding gas after 25 years, then you have a darned good system. Isotherms are notorious for slight leaks due to some kind of less than top quality fittings they used (I think). Yours must predate that era; mine does not.

I have two Isotherm systems, one for a fridge and one for a separate freezer. I have to add gas every year or two to both of them. Contrary to some advice you've received, it is an easy DIY job requiring an inexpensive can tap and pressure gage rig, and small cans of compatible refrigerant. You can do your own googling to locate the specific items. My system is R134a so I was able to bring several cans of refrigerant from the U.S. (they are hard to buy in Europe), but the Isotherm systems have such tiny capacity that I haven't even finished the first can yet after many years of doing this. I have heard that you can buy small cans of ersatz R12 which is compatible with your oil, but I don't have specific knowledge and you will have to figure that out for yourself.

To fill them properly you need to carefully follow a particular procedure, and note that overfilling them will harm them. There are detailed instructions on Richard Kollman's excellent site about marine refrigeration systems; looky here: http://www.kollmann-marine.com/servicing sml refrig.aspx


With such an extremely slow leak, I would not bother vacuuming down the system PROVIDED the new gas (RS-24/r426A?) is compatible with the R12 already in the system (N.B.! If not, then you will have to have the old gas taken out and the system vacuumed down, by a pro). I would just get the system properly charged (one way or another) and see how it works. Dollars to doughnuts it will be good for another 25 years. If you do end up replacing it, don't use a carpy cheap capillary tube system like the Isotherm and the other consumer grade systems sold for boats. Buy one with a proper Thermal Expansion Valve and receiver, which will allow you to tap both high and low pressure sides and charge exactly. On the tiny systems used in boats, the cap tubes are so microscopic that the slightest impurity will clog them and that's it -- end of life. TEV systems are much more robust.
 
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How do you know it’s a small slow leak? Just putting me re gas in may get it working but does not solve the issue, fridge systems are not designed to leak! if repaired correctly they will not leak again until something fails. Poor manfactures fittings are replaceable.

Also R134a is not a drop in for R12, different oils and different operating pressures.

Regarding TEVs they fail regularly as well and also block as they have a very small orrifice and often strainer / filter built in
 
Daverw said:
How do you know it’s a small slow leak? Just putting me re gas in may get it working but does not solve the issue, fridge systems are not designed to leak! if repaired correctly they will not leak again until something fails. Poor manfactures fittings are replaceable.

Also R134a is not a drop in for R12, different oils and different operating pressures.

Regarding TEVs they fail regularly as well and also block as they have a very small orrifice and often strainer / filter built in
Click to expand...

Certainly not 134a. You need something like this: https://www.gas-servei.com/en/componentes/sustitutos-directos-del-r-22/r-426a--rs24-

Certainly refrigeration systems should not leak, ideally. However, chasing a tiny leak (adding gas first time after 25 years!!) can be more trouble than it's worth.
 
The problem is trying to buy it with FGas cert, unlikely from UK supplier, RS don’t deal direct and minimum cylinder 2 kg. RS24 does not have a good record from the systems I’ve seen.

Unfortunately in the refrigeration game retrofitting has a high failure rate.
 
I spent 3 years trying to keep an old Isotherm running. New gas, wiring etc....

Last season the compressor died so I had to get a new system.

Now its fitted (reasonably easy) I wish I had done it 3 years ago.

Replace.
 
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