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 Post subject: Aircon conversion to R134
PostPosted: Tue Oct 06, 2009 7:34 pm 
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I was looking to get my aircon modified to R134 as it is still on R12. It was working until the other week but now seems to have failed. I was going to take a chance on just getting it converted to R134 and see how long it works for, before taking it in next year for a full overhaul.

A local guy says you just need to "drain the system, replace the high and low pressure connectors, vac and dry the system to remove any moisture, put in oil and a green dye, then regas (with R134) and test the system"

I was thinking I should replace the receiver/dryer as I don't know how long it's been fitted. I believe there is a kit of parts available for the R134 conversion. Does anybody know who can supply the kit? Alternatively where can I buy a replacement receiver/dryer. Porsche want £130 plus VAT for it.

Ebay item number 260462932575 will this be OK, it's listed for various 928's including the S4 CAT but mine's a 1989 non CAT.


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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Oct 07, 2009 12:37 pm 
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If you're thinking of conversion (though R12 a bit colder when working) then the doyen of 928 aircon to talk to is Richard Armstrong (google Ritech Systems) in Wiltshire.

This is what Rich said to me when I was contemplating conversion (not got round to it yet):

The simple way is to change the gauge fittings (assuming there is no
leaks), use a conversion system which dumps a gas mix and special mix
PAG oil in and refill with R134a.
Trouble is the seals are not compatible with the new oil so they will
fail eventually, but that may be years.
The complex (and expensive) way is to re-seal the compressor, change all
the 'O' rings in the system, re-fill with synthetic oil and R134a. Then
of course the condenser fittings may be corroded and disturbing them
causes a leak, and its new condenser time!

Sounds similar to what you were told but I think the oil is pretty special to effect conversion.

Best thing is to contact Richard, as I know next-to-nothing about aircon!

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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Oct 07, 2009 5:37 pm 
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Thanks for the advice, there's a guy nearer to me called Christopher Sanderson and I'm going to take it to him, he's been recommended on this forum.
There's no point in me messing with it. However I did find a company in the USA selling the later type receiver/dryer units for $11. A bit cheaper than Porsche, who quoted £130 plus VAT.


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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Oct 07, 2009 6:01 pm 
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Not car specific but I deal with A/C as part of the day job. Drop in gases need new sealing O rings & the receiver dryer needs changing which it should be every time it is opened up. Some hoses may need replacing as the drop ins can be more prone to finding leaks. The problem is that to drop a replacement gas in will derate the cooling system as they are less efficient. The best gas I could find only gave 85% of the ax cooling capacity of R22. Some of the drop ins can be quite expensive as well, not so relevant with a car system but significant when it is 500kW!

Try reading here http://www.refrigeration-engineer.com/f ... php?t=1727

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 Post subject: Re: Aircon conversion to R134
PostPosted: Tue Oct 20, 2009 9:38 pm 
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I got this done, went for the cheapest option. Had the system regassed with R134 after purging it of the old gas etc.
Replaced the receiver/dryer.
Will see how long it lasts, and probably get a full overhaul/seal replacement done next year. At the moment it's working....but now the vacuum operated heater system has thrown in the towel, so I can only get cold air to the screen and centre vents.
I've ordered a vacuum pump to assist in finding the leaks!


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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Oct 21, 2009 11:04 am 
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You might want to look at RS24 (R426A) instead of R134, it is I direct drop in replacement for R12, you can simply evacuate the R12 and re-gas it with RS24, don't even need to change the oil as RS24 will work fine with mineral oil, the existing seals and o-rings should be fine too. The only thing you need to change is the receiver/dryer, which I believe you should replace every time anyway.

Some more details here http://www.rscool.com/RS-24.html.

A previous owner has converted mine to RS24 and it works perfectly.

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 Post subject: Re: Aircon conversion to R134
PostPosted: Tue Oct 27, 2009 5:33 pm 
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I'm just concerned now as to how much oil there is left in the system. The aircon is working OK but when the guy replaced the gas/converted it to R134 would that mean he drained or sucked out all the old oil as well?
His receipt says that he put in 25ml of oil which would probably be OK if it was in addition to what was already there?
I tried to contact him to ask but he's not got back to me. So there are 3 possibilities. A. it's got plenty of oil in plus the bit he added. B. it's only got 25ml in it now. C. it's a misprint on his receipt and he meant 250ml
Can you remove the old oil, and do you think he would have removed it?


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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Oct 28, 2009 1:05 pm 
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I thought that was the problem with converting form R12 to R134, you need to remove ALL the old mineral oil and replace it with new synthetic oil, as the R134 gas doesn't carry the mineral oil. Also it's not very good for the original seals and will eventually destroy them. That's why RS24 is less trouble, as it works fine with the original oil and seals.

I only know this because I was concerned when I saw the RS24 sticker on my car as I had never heard of it, so I did some research to find out what it was. I haven't actually found anything that explains the downside of RS24, but I guess there must be one, otherwise I don't know why anyone bothers going from R12 to R134, it probably costs a fortune !!!


UPDATE:
Hmmm I think I might be right.... RS24 looks quite a bit more expensive to re-gas oh well !!!

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Mitsubishi Shogun LWB 3.0 V6 auto 1998


Last edited by geo on Fri Oct 30, 2009 10:22 am, edited 1 time in total.

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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Oct 28, 2009 7:45 pm 
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Well, looks like I'm going to have to get it done again, and specify replacement of all the oil. The guy who did it is not returning my calls or texts.
However it is working, but I'm not going to use it until it's been done again.

Can anybody shed some light on the air con oil quantity/system for me? I believe the compressor has an oil resevoir. Is this separate from the oil in the refrigeration system, or is it the same system?


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 Post subject: Re: Aircon conversion to R134
PostPosted: Fri Nov 06, 2009 9:24 am 
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An update on this one.

The aircon lasted about 2 weeks and then stopped working. I took the car to Loe Bank Motors (Porsche specialist) they looked at it with their UV lamp and determined that the condenser was leaking.
So they are going to fit a new one, and replace some rubber seals, plus the guy who did the R134 conversion only changed one of the valves.
To change the condenser half an hour "if the bottom bolts were left out last time it was changed" and 3 hours "if they were not"
Better get my cheque book ready. It'll be the 3 hours.


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 Post subject: Re: Aircon conversion to R134
PostPosted: Sat Mar 09, 2019 9:09 pm 
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Hi,
Is this still a live forum? I am looking for some aircon advice on '87 S4

Cheers


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 Post subject: Re: Aircon conversion to R134
PostPosted: Wed Mar 13, 2019 5:30 pm 
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My experience with my '84 S2 : when I acquired the car the AC didn't work, so I consulted the engineer who looked after the -40 test chamber cooler I worked with. He helpfully showed me what to do so I got to learn a bit too. I bought a fittings conversion kit from a web site in Florida, no idea who it was as it was fifteen years ago, the kit comprised aluminium conversion sleeves which screwed on the ¼" R12 ports giving the push fit R134a ports. First we found there was no pressure at all in the system. Not surprising when we found the condenser had loads of corrosion damage, shot full of holes. I sourced a new one from the USA which from recollection was about £350, which was identical to the original. When I went to fit it, the O rings were green which I'm told is ok with the oil. We wondered if it might have been converted, we probably should have assumed the oil hadn't been changed, but we left it. We hooked up a laboratory type Edwards rotary vacuum pump and pumped it to the lowest pressure, left it pumping overnight, then turned everything off all valves shut, after several hours there was no discernible leak, so my friend ran in the R134, the system worked beautifully till I was obliged to lay it up on a SORN for several years. Not surprisingly the gas had mostly leaked away. I regassed it and it's still working fine after another four years. I will re check the gas before long, but I don't expect it will need much, maybe I've been lucky.
The price of R134 has rocketed since I started so it doesn't do to make mistakes, I'm told that one could use Propane as a substitute, however the prospect of a prang releasing near on 1kg of propane into the mess doesn't seem wise! Might be ok with a static setup....


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 Post subject: Re: Aircon conversion to R134
PostPosted: Thu Mar 14, 2019 9:04 am 
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Soupytwistii wrote:
Hi,
Is this still a live forum? I am looking for some aircon advice on '87 S4

Cheers


Still active, though you’ve resurrected a very old thread!

What did you need to ask about your S4? If it’s MY87 I expect it’s on R12 unless already converted?

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