Classic Audi Technical Mech/Tech Interior » Aircon gas conversion questions

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Old 29-09-21, 07:19 PM   #11
terrywindy1
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https://www.ebay.co.uk/itm/Audi-100-...-127634-2357-0
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Old 30-09-21, 10:43 AM   #12
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Originally Posted by Hanuman View Post
After doing some further research...

The R134A alternatives were also phased out as they had, as I understand it now, some proportion of R12/freon.

Accord to some initial blurb that I've read, molecule size leads to increased leak down rates. Which with a system that has been run down already may be further exacerbated.

The oil used for R12 is not directly compatible with R134A in that it doesn't readily mix, and therefore doesn't transit the system, but some folk have simply added the normal service amount of R134A-oil to the system, and the appropriate quantity (by mass) of R134A gas. This lead to system problems in some cases as the overall pressure is lower. Later pumps provide a higher output. A part of the original service change was to swap some pressure sensors. A fudge/fix has been to add the appropriate amount of R134A gas, plus a bit more. How much is a bit more? 10%? lick finger, place in airstream...

If the system pressure is too low, then the pressure sensor doesn't activate, and the controller doesn't activate the clutch, and so the system doesn't get cold. I've yet to delve into the diagnostics on this. That'll be for next spring, now.

Parts
Green o-rings.
I'm disinclined to rip everything apart unless I really must. Reports from some sources suggest they've got away with it. The easy ones to swap will be pump inlet outlet, drier, radiant a small few others. 7-Zap hopefully will lead me to these.

Pump seals.
I've one brand new pump. At a suitable point, I may swap it in along with a few other bits, but for now, i'll see what I can get away with.

Pump.
I actually have accumulated a spare of each type of pump. They're not interchangeable on the V8s. the early car plumbing ('90 and '91 models) at the pump is very different to the later pump. Again, I may take a moment one day to work out if the later plumbing can be swapped in. In this case, it will likely negate the need for the new pump!

Nozzles.
Apparently, these are different, as the hoses/fittings for filling up the system changed between R12 and R134A. Larger later, I think. I have spare bits and pieces of plumbing from the scrapped V8, plus somewhere I picked up a few bits for the upgrade.

Tools
The only thing I've encountered as a problem at present is the Aircon service tools that I acquired a while back don't include the correct puller for the '90 car's Aircon clutch. Right diameter, wrong thread. As far as we've got so far, it may be M24x1.5 thread. Loads in the states and Germany.


...and that's as much as I've been able to glean so far.
That's very helpful. I also need to replace a hose connection which split on removal, otherwise I could bolt the lot up myself.
I aim to get it all fitted to the car, and then leave that pipe and the accessible O rings to be fitted by a specialist prior to recharging. I recall the advice to always fit a new drier-which seems sensible given the ones i have have been open to the wet air for months/years, so I'll look for one of those too.
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Old 01-10-21, 06:07 PM   #13
terrywindy1
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When I changed mine from R12 ,I did find the thread on the R12 drier was a different size
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Old 01-10-21, 07:30 PM   #14
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Originally Posted by terrywindy1 View Post
When I changed mine from R12 ,I did find the thread on the R12 drier was a different size
did you change it all yourself, DIY? In which case, how in-depth did you go, and how was the system afterwards.
Every bit of detail useful.
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