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
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>
>
> -----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
> >
> -----
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