Air Conditioning

kennedichimney

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I think my W124 E220 needs an air con re-charge. What refrigerant can be used? My recollection is that R14 was standard, then R112a and now I see R134a is advertised. Are all these refrigerants compatible, and has anyone any experience of the DIY kit (EZ Chill, made by interdynamics europe) being marketed by Halford's?
 

cleverdicky

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jeez thats going back to the dark ages. Are you certain.?

Quite possible (and likely) you had R12, but the other two are from the time of benz himself.

Whatever you did have, the crucial thing is the oil. The 2nd crucial thing is the t.e.v. or expansion valve, as it crucially requires certain operating pressures.

The oil is miscible with refrigerant, and for this reason you need the right oil with the right gas.
They just cannot be mixed !
And even with a chemical flush it only sometimes works without causing sever damage and failure.
Thankfully the retrofit to 134a was possible from R12, as it was developed with this in mind, but only after a good flush and oil change.

You really really need to know. If in doubt assume the worst and get it redone properly.
Check your system for leaks (pressure test) a good clean, new oil and then refill to R134a.
And fingers crossed.

If you did have R112 or R14, it still might be possible after all the above, but you will need to do some research (or pay someone) to check gas operating properties are in a similar range, and that the TEV if need be has been changed.
Otherwise forget it. Seriously major job ripping dash out.
Even the the c.o.p. is an unknown to me. Which means you might have a much different performance (cooling ability) than is possible.
 
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kennedichimney

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Thanks for the advice cleverdicky. I think there may be a misunderstanding here. I did not mean that my car aircon had been filled with all these refrigerants at various times, simply that I was aware of these differing types being used on various cars over the course of the last twenty or so years. Since the W124 goes back nearly thirty years since first production and more years beyond that in the design stage I wondered what refrigerant had been specified at the start and whether there had been any changes during the W124's production life. Given that information, what effect would this have when trying to re-charge the system, as presumably R134a is the (only?)generally-available refrigerant now? :) Do all traces of the previous refrigerant have to be removed before re-charging?
 

cleverdicky

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Pretty much but any left will be removed in the process. A tiny amount will always be trapped in the oil but will do no harm.
In the 'old days' and the odd time ive done this for mates, I would use a blend of different gases to get good cooling at as big an engine range as possible.
(different gasses, different properties and different operating pressures)
So was a bit of an art ;) )
Although wouldnt go down well these days. plus the gasses available are a bit different.
The problem for you is the oil. And what oil in there you have that is compatible with oil from todays gasses.
A good fridge engineer, a proper one could easily tell you by looking at the pressure of the gas you have in there still?? in ambient temperature, and using that info to check with a comparator. But I doubt the guys in quick fit or similar places would even know what that was.

Best thing you can do is get the details from your compressor. And if possible any stickers or info from when the car was made. Although the list of gases that could be used is long I suspect it was probably R12 as the most common one until late 80's.
If it was R12, it would mean a flush still but would take 134a.
If it didnt, there is no way to tell what operating range the comp and tev would operate in.
Even if you did flush it.
You really need to find what it had from when fitted and go from there.
 

cleverdicky

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Also in answer to your other question. Yes its illegal to use r12 these day, and even though its no longer made or supplied I suspect there are some stocks left for emergency replacement by some.
But I should imagine a small dumpy of it now could be worth as much as your car to the right buyer :shock:
 

giuseppe

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It should be written on the nearside in the engine bay on the electrical box
 

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