[s-cars] AC low side recharge adapter

[Tom Green]

Exactly correct on the low pressure switch, Steve.

But, there have been many posts on this list that claim a DIY recharge
using that port.  I am inquiring how.  If someone here has broken the
code, please share the information.

If you have to break the system open and find fittings, braze lines,  
then
evacuate system, then it is not really a DIY job unless you are in the
ACR business.

Perhaps the R12 system is not DIY anymore, but the R134a cars that
have just lost a little charge in 12 years don't need a complete leak
check and evacuation, but just a quick top off.  If I could also check
the system balance and not just high system pressure, that would be
an added plus.

Tom

On Jul 3, 2007, at 11:47 AM, Young, Steve wrote:

>
> Having read these A/C posts with interest, I'll add my $0.02.  I  
> will be
> looking into my A/C system soon, as it provides no cooling.  So bear
> with me as I have done no investigation to date.  If the low pressure
> cutout switch is the type that screws onto a threaded schrader valve
> port, any refrigeration supply house should have a tee fitting that
> could be installed between the A/C line port and the cutout switch
> leaving an additional port for gauge hookup.  This assumes that  
> there is
> physically enough room to add the tee, and then orient it so that a
> gauge hose can be attached.  It also assumes that Audi did not use a
> fitting with a non-standard thread.
>
> http://www.grainger.com/Grainger/items/3GD02
>
> An alternative would be the pick up a braise in port fitting and  
> install
> it in a manageable place on the low side of the system.  If you system
> is already empty, this option will take about 30 minutes to install by
> drilling the proper hole in the low side line, and braise in the
> fitting.
>
> http://www.grainger.com/Grainger/items/3X729
>
> Or use something like this.
>
> http://www.grainger.com/Grainger/items/3WU91
>
> YMMV, and please verify the line size before purchasing.
>
> Regards,
>
> 				TRANE
> Steven Young
> Local Operations Manager
> Albany Office
>
>
>
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of Tom Green
> Sent: Tuesday, July 03, 2007 10:31 AM
> To: s-car-list at audifans.com
> Cc: calvin at earthlink.net
> Subject: Re: [s-cars] AC low side recharge adapter
>
> This issue has been revisited many times without any definitive  
> answers
> given to the list.  The most often asked is about adapting a gage  
> set to
> the low pressure port for a DIY recharge.  But no one has offered any
> specific details for this even if they said " I did this myself".   
> Even
> the local dealer service manager claims they never use the low  
> pressure
> port, only connect to the high pressure port at the condenser,  
> evacuate
> and refill a measured charge with the engine off, and measure the high
> side pressure and interior duct temperature for any fine tuning of the
> charge with the engine running at 2K rpm.  There is some risk of
> introducing liquid refrigerant into the compressor by using the low  
> side
> port if you are not careful or overcharge the system even though shops
> use this system on most vehicles, and of course, the high side  
> pressure
> will burst a DIY can and will only allow a recharge with the  
> compressor
> off.
>
> My high side valve is on the front right side of the condenser and
> easily accessible on the S6.  I don't know about the R12 systems on  
> the
> S4.
>
> Is there someone on this list who can put these issues to rest?
> That is, can someone provide a source
> for a low side adapter?  Does anyone have specific details of the
> differences in the URS4 systems using
> R12 and the URS4/6 systems using R134a?
>
> Tom
>
>
>> Date: Mon, 02 Jul 2007 21:24:49 -0400
>> From: Kent McLean <kentmclean at comcast.net>
>> Subject: Re: [s-cars] AC low side recharge adapter
>> To: s-car-list <s-car-list at audifans.com>
>> Message-ID: <4689A561.5060607 at comcast.net>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Aaron Ryba wrote:
>>> Like others have mentioned I took off the low pressure switch (F
>>> 73) located in
>> the right
>>> plenum and planned on filling her up there however it seems like the
>>> threaded male connection with the schrader valve there is a  
>>> metric 10
>
>>> mm thread size which won't work with anything I can get at Autozone
>>> or Advance Auto parts. I am trying to avoid spending $100 bucks on
>>> the high end manifold gage set or paying a shop $120 to fix it for
>>> me.
>>
>> I'm almost in the same boat.  With 3 Audis with weak or no AC, I
>> thought I'd be better off investing in the equipment and doing it
>> myself. I bought the not-quite high-end manifold gage set ($60 at
>> Robbins, a supplier to mechanics in S. NH, not the $39 set at the
>> local national consumer chain.
>> Plus another $30 in the R134a-specific hoses.). I bought the R134a
>> adapters.
>> I haven't gotten around to actually doing the conversion(s) yet.
>> But my
>> understanding so far is that the gage sets needs to tap into both the
>> high- and low-pressure sides of the system, so you still need to have
>> access to a low-pressure side valve.
>>
>> My am also under the impression is that the valve on the  
>> compressor is
>
>> meant to drain the oil from the compressor, but as it is on the low-
>> pressure side,
>> -- and here I'm not 100% sure/convinced -- it can be used to  
>> recharge 
>> the system. I'll leave it to someone with more experience to confirm
>> or reject that idea.
>>
>> --
>> Kent McLean
>> '91 200 TQA #1, for sale
>> '91 200 TQA #2, no name yet
>> '94 100 S Avant, "Moody"
>> '89 200 TQ, "Bad Puppy", up in smoke
>
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