Could be the compressor front seal. The seal is just an oil film between very close fitting parts.

Thanks, Tom Hargrave
www.kegkits.com – Electric Brewery Info
www.towercooler.com – Beer Tower Cooler
http://goo.gl/niRzVw - My Amazon Store
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http://www.hackpilot.com/roadkill/ - A little twisted humor

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of Stephen Grisanti
Sent: Monday, April 13, 2020 11:19 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: found some freon 12 should I recharge old AC

 A Samba thread on R134a conversion from a few years ago involved replacing all the hoses.  He removed them and had a shop put the stock ends on new barrier hose, as I recall, and I think he reported it cost about $200 at the time.
I can never find the link when I want to but it involved an '87 Westy like mine. Stephen
    On Monday, April 13, 2020, 10:57:02 PM EDT, David McNeely <davmcneely40@gmail.com> wrote:  
 
 Tom, I don't know if your response was meant for me.  I converted to R134a long ago.  Cools great when it gets a new charge, but leaks down over half the summer, and no one can find the leak.  So, I thought -- based on Denis's comment to the original poster, "Aha, might be hoses."  mcneely

On Mon, Apr 13, 2020 at 6:56 PM Tom Hargrave <thargrav@hiwaay.net> wrote:

> If you are considering swapping to R134a, by now the old hoses should 
> not be an issue because they have been fully saturated with 
> refrigerant oil and won't leak.
>
> But like someone else mentioned the tough part will be to find someone 
> willing to convert your system. Most AC shops dumped or upgraded their 
> R12 recovery systems long ago, when the R12 to R134 conversion 
> business finally went away.
>
> You will have three issues with a conversion.
>
> 1. A conversion drops about 20% of the system's cooling capacity.
> 2. The expansion valve is the wrong size and should be replaced.
> 3. The compressor front seal will leak R134a because its molecule size 
> is smaller than R12.
>
> In other words, to do it right you have to replace the compressor, 
> receiver dryer and expansion valve and you still lose about 20% of the 
> system's capacity.
>
> You are better off testing for pressure. If your system still retains 
> any pressure by now, have it serviced and drive it as is.
>
> Thanks, Tom Hargrave
> www.kegkits.com – Electric Brewery Info www.towercooler.com – Beer 
> Tower Cooler http://goo.gl/niRzVw - My Amazon Store 
> www.brew-control.com – Electric Brewery Marketing and Direct Sales 
> http://www.hackpilot.com/roadkill/ - A little twisted humor
>
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On 
> Behalf Of David McNeely
> Sent: Monday, April 13, 2020 3:21 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: found some freon 12 should I recharge old AC
>
> Dennis, you said that the original poster's "... hoses are also old 
> and not designed for R134a."  Some years ago, I had my AC system (1991 
> VW Vanagon GL Campmobile) converted to R134a. Based on extensive 
> investigation before having the conversion done, I believe everything 
> except hoses was done. The system has never held refrigerant well 
> since.  It will cool beautifully after a fill, then drop off in 
> effectiveness until it is kaput about half summer through.  It has had 
> dye added to the refrigerant, and searched for leaks, with none 
> evident.  Could the old hoses (originals) be the problem?
>
> Thank you, mcneely
>
> On Mon, Apr 13, 2020 at 12:54 PM Dennis Haynes 
> <d23haynes57@hotmail.com>
> wrote:
>
> > FWIW since you are asking this question you probably should not be 
> > servicing the AC system without some help. Since the system has been 
> > neglected it is likely to be contaminated with moisture and the oil 
> > probably also needs to be serviced. The proper procedure would be to 
> > test for pressure and have anything inside it recovered. Good luck 
> > finding a shop with R12 recovery equipment. Sell the cans. You will 
> > need about 1,300 grams to fill an empty system. AC systems are magic.
> > Even under pressure they somehow manage to get moisture inside. Most 
> > likely small leaks on the suction side including the compressor 
> > shaft
> seal.
> >
> > If the system was really empty for a long time then the 
> > receiver/dryer should be replaced and it would be a good idea to 
> > change the compressor oil and plan to convert to R134a or one of the 
> > other "magic" refrigerants out there.
> >
> > Then you pressurize the system with nitrogen and ensure it can hold 
> > pressure, at least overnight.
> > Then you need to evacuate the system. The longer the better. You 
> > want to boil off all moisture and other contaminants in the system. 
> > A small amount of moisture can play all sorts of havoc. The nastiest 
> > is ice crystals blocking the expansion valve and causing the 
> > compressor to dead head. The
> > 85 does not have much in the way of safeties and even better systems 
> > this will often result in blown compressors, hoses, switches etc. 
> > Then charge, by weight. They say R134a should be 80-85% of the fill 
> > for R12. I find the Vanagon really works best 1,300-1,400 grams. 
> > Don't forget the add the required amount of compressor oil. If still 
> > some mineral oil in there use Ester. If you really got the system 
> > cleaned you can use the preferred PAG oil for R134.
> >
> > The earlier AC systems are a bit disappointing especially the campers.
> > Upgrading the condenser to one of the parallel flow universal ones 
> > help a lot. They also allow for better airflow helping both the AC 
> > and
> radiator.
> > Your hoses are also old and not designed for R134a. Typically though 
> > the common leak points are the condenser, the compressor and the 
> > receiver dryer.
> >
> > Dennis
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On 
> > Behalf Of Spencer Allen
> > Sent: Monday, April 13, 2020 10:36 AM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: found some freon 12 should I recharge old AC
> >
> > Found two 1LB cans of R12 in my late uncles garage. My 85 Westys AC 
> > worked when I bought it 20 years ago but only used it a couple of 
> > times at first and then not at all. It's probably been 15 years 
> > since I last used it and it blew cold during that time. Since then 
> > on the occasions when I turn it on just to run it no cold air comes 
> > out. I hear this old stuff is really expensive so since I have these 
> > (free) cans sitting here I'm tempted to hook up my hoses and recharge system.
> > Any thoughts or input on this idea?Spencer85Westy
> >
> -----
> No virus found in this message.
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>
>  
-----
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Checked by AVG - www.avg.com
Version: 2016.0.7924 / Virus Database: 4793/15886 - Release Date: 08/14/18 Internal Virus Database is out of date.