[s-cars] FW: A/C DIY 134a recharge

[Mark Strangways]

An interesting little tidbit...
They are to do away with R-22 with in the next 10 -20 years..
The replacement is so nasty that it has to be stored in a 600 PSI container,
your van (a/c service) needs to be white, and needs to be air conditioned
for the summer months.
This stuff apparently is incredibly temperature sensitive... and will expand
greatly at modest temp rises....

Mark S
----- Original Message ----- 
From: <Djdawson2 at aol.com>
To: <tr0910 at softhome.net>; <S-CAR-List at audifans.com>
Sent: Tuesday, June 08, 2004 1:50 AM
Subject: Re: [s-cars] FW: A/C DIY 134a recharge


> In a message dated 6/7/2004 9:12:29 PM Mountain Daylight Time,
> tr0910 at softhome.net writes:
>
> > Well now its my turn and I have the juice, if I can just figure out a
> > way to get it in there.  Does everyone still agree it can't be done by
> > the shadetree mechanic??
> >
>
>
>
> Tim,
> To answer your question...  If you've got a can of 134, and nothing else,
> chances are good that the answer is no.  Here's why:
>
> When your system is running (engine on, compressor engaged) the typical
> pressures on your system will be roughly 20 psi on the low side
(compressor inlet)
> and around 250+psi on the high side (compressor outlet).  Hook up a can of
134
> to your high side (the only port available on 134 S4's) and it may
explode.
> You can't charge your system because the pressure in the can is less than
the
> port pressure.
>
> If you were to shut the system down... engine off... the system pressure
will
> equalize.  What I have typically seen on a shut down system is 60-80 psi.
> This affords you some opportunity, but is somewhat risky.  You could,
> theoretically, get the 134 out of the can and into your system by heating
the can enough
> to generate internal pressure that exceeds the system pressure.  Me... I
> wouldn't do it for several reasons.  1st, it isn't exactly a safe
approach.  2nd,
> you have no idea how much your system needs.  If you have gauges, you
could
> add a little, hook up the gauge and engage the system, and keep going
until
> you've reached a reasonable high side pressure reading... or quit when the
cooling
> output is adequate.  This still isn't a great approach, since you will be
> introducing considerable air into the system with repeated hooking up of
the can,
> then the gauge, then the can, etc...  Further, you aren't able to see a
low
> side reading, which is an important part of the equation.  Finally, Audi
hasn't
> provided us with a sight glass, which further confuses the charging task.
>
> IMO, the best solution for the shadetree mechanic, is to take your car
into a
> good A/C shop and have a low side port added to the system.  This will
> obviously involve opening your system up.  Once the port is added, replace
the
> receiver/dryer, and have the system evacuated and recharged.  This doesn't
save you
> any money now, but would at least get you ready for the next time.  And
there
> will likely be a next time... as you must be leaking somewhere. And
through
> your new low side port, you can charge as you need to in the future.
>
> HTH,
> Dave (A/C certified, believe it or not) in CO
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