[s-cars] AC recharge

[Tom Green]

>
Topping off the R134a system is relatively simple.  The A8/S8 list has  
a Robert Waterloo discussion on how to do this, including why you  
might not want to do it.  Then, look
at the August 2007 archives of this list for much discussion on the  
URS4/6 systems.  I use this adapter, modified to allow both schrader  
valves to operate in unison so you
can gage the system and completely empty the 12 oz cans:

FJC Air Conditioning Products - R134a Tank Adapter (6016)

It is disappointing that no URS4 owner has yet "carried the message to  
Garcia" and provided a BTDT report on the connectors or adapters  
needed to top off the R12 system
since so many report hoarding cans of refrigerant that they don't know  
how to use.  There are safety, economic and environmental issues (and  
regs) to consider, but you
need all the information to make an informed decision.  There have  
been numerous posts similar to bob's below, but all gloss over the  
fact that the fitting for the low pressure switch does not match any  
common manifold gages or tank fittings.

If you have R12 you are not going to use, sell it to a certified shop  
that can immediately put it in a recovery tank and pay you big bucks  
for it.

Tom

> -----Original Message-----
> Date: Thu, 7 May 2009 04:55:35 +0000
> From: "Kunz, Bob" <bob.kunz at hp.com>
> Subject: Re: [s-cars] AC recharge
> To: Theodore Chen <tedebearp at yahoo.com>, "s-car-list at audifans.com"
> 	<s-car-list at audifans.com>
> Message-ID:
> 	<540E0B723B94954CA9F98ECACA9316AE3204A85AB1 at GVW1098EXB.americas.hpqcorp.net 
> >
> 	
> Content-Type: text/plain; charset="us-ascii"
>
> Green aliens from Planet Osmosis made Theodore Chen say...
>
>> the air conditioning system in my '92 works, but not very well.
>>
>> a shop said they'd recharge it with R-12 for $120, or convert to  
>> R134a for $140.
>
> Ah, summer arrives and the inevitable A/C issues crop up. You should  
> keep the system R12 if possible because of all the issues already  
> pointed out.
>
> The low pressure port is the low pressure switch (in the plenum on  
> the passenger side). You remove the switch and bridge the connector  
> (keeps the system from thinking pressure is too low), the system  
> remains closed because there is a Schrader valve in there. If you've  
> got manifold gauges use them of course. Low side pressure depends on  
> ambient. A couple of data points are (degrees F, PSI) (77,29.5),  
> (86,29), (95, 30). This is with the engine at 2K RPM, max cool, high  
> fan. Some compressors (my '86 does) have a low pressure port on them  
> in which case the pressures are about 3 PSI lower taken at that  
> port. If you need to play with the high side, you also remove the  
> switch and leave the cable connected (makes the system believe you  
> are not over pressuring the system on the high side).
>
> Remember the rule about recharging R12 systems (EPA tech hat on  
> now)... you CAN top up systems that are leaking but if you need to  
> open them you MUST recover the refrigerant. That's what makes  
> complete service of R12 systems pricey. $140 means the shop you  
> queried is not following rules. And although R134a is the same stuff  
> in duster cans, if you are dealing with it in a refrigeration system  
> you must recover the R134a. Go figure!
>
> --bob
> '86 5Ks Avant
> '99 A6 Avant
> '02 TTQR
> '07 Q7 4.2P