Convert/retrofit to R134a or stay R12?

[SAJanesick - Bellsouth]

Kenneth -

The research I found said that R134a molecules are smaller than R12 and will 
of course leak through a bad fitting, but perhaps of more importance, they 
will actually leak over time through the wall of the R12 hose itself.  R134a 
hoses have some type of additional liner that makes them impervious to the 
refrigerant when under pressure.

When I tried a direct R134a replacement, I not only got mediocre cooling, 
but it also leaked over time.  High side pressure when running dropped by 
about 50% over the next 4 weeks.  I think my leak was mainly in the 
compressor as it would leave a drop or two of oil every day on the floor.  I 
assume the compressor has a poor seal and perhaps the R134a is carrying some 
lubricant out with the leak, but who knows?

The drop-in that I am going to try is a hydrocarbon based refrigerant 
(probably propane or butane with some additives).  They claim all sorts of 
improvements over both R12 and R134a - and bigger molecules(!?!).  I'll also 
be dumping in a can of stop leak they made designed for rubber parts and 
seals, so perhaps that will also help with the compressor.  If not, then I 
guess it's a new compressor.

I bought a receiver/drier from AdvanceAuto.  It has the two Schraeder valves 
and its label says it's a Gilmore 70-3700 (090422C) and of course, Made in 
China.  It comes with the green o-ring for R134a.  With their online order 
discount it was $18 and change and had SKU# 5892562.  In the store it's 
something like $23.  I have not yet fit it, but it looks about right from a 
quick glance.  I also bought a new orifice tube from AutohausAZ but I do not 
know if it is a standard or variable.  It says it's a Santech PN:MT0097-1 
and the AutohausAZ numbers are 659 54017 066 and 443 271 191 A and of course 
it was Made in China.

I was planning to install everything this afternoon but we just got a call 
from my wife's mother who apparently woke up with a detached retina.  All 
bets are off for afternoon A/C work today, but I'll let you know as soon as 
I get to it.

Later...

        - Steve Janesick

----- Original Message ----- 
From: "Kenneth" <auditude at cox.net>
To: <200q20v at audifans.com>
Sent: Tuesday, June 18, 2013 2:28 PM
Subject: Re: Convert/retrofit to R134a or stay R12?


> Thanks Tony and others for the reponses.
>
> Can you tell me if there is an Audi part number for the parallel flow 
> condenser, or is that an aftermarket type of a change?
>
> Out of curiosity, is the parallel flow any better if retaining an R12 
> system?
>
> I believe I can take the lines to a hose shop to have them replaced with 
> teflon barrier type, reusing the ends.  Not sure what that would cost.
>
> Maybe you're saying it will be trouble with the hoses, because you're 
> putting in a completely different condenser with different connection 
> locations, or even connections for that matter?
>
> What about the "variable orifice valve."  It's supposed to be a spring 
> loaded type that compensates for lower compressor output at idle, etc. 
> Some say it works, other say it's more snake oil.  In concept it sounds 
> good.
>
> I saw two versions of receiver driers.  One had shraeder ports on the 
> sides, the other didn't.  What's the difference other than cost?  The 
> valved one was cheaper, actually.
>
> Thanks!
>
> Kenneth
>
> ---- Tony Hoffman <auditony at gmail.com> wrote:
>> You can read day and night about this conversion on the internet. The 
>> long
>> and short is this:
>>
>> 1. The 134A molecules are smaller, so they will leak just a bit through
>> your hoses.
>>
>> 2. Change the reciever drier (under the raintray cover on the right side 
>> of
>> your car)
>>
>> 3. The factory condensor is of the "serpentine" type, as opposed to the
>> parallell setup of the newer cars. 134a does not cool well with 
>> serpentine,
>> so you should change that over to a paralell flow. I am in the middle of
>> this on my 89 100 right now. The hardest thing to deal with is the lines.
>>
>> So, unless you are willing to do that, stick with R12 or an R12 
>> substitute.
>>
>> HTH,
>> Tony
>>
>> On Tue, Jun 18, 2013 at 12:38 PM, Kenneth Keith <auditude at cox.net> wrote:
>>
>> > I have to replace the compressor on my 200q20v.  Have people had good 
>> > luck
>> > retrofitting to R134a, or is it better to stick with R12?
>> >
>> > I'm in hot Arizona, so a marginal system is not desirable.
>> >
>> > I get the impression from initially searching that a retrofit isn't
>> > totally terrible.
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