from what I researched on the net (and I have to do the job myself today)
the only difference in respect to oil is that systems with any remains of
r-12 (and the corresponding mineral oil) MUST use PAG oil if oil is added.
The standard oil that is used with r-134a apparently causes problems when
mixed with the old stuff.
You can buy cans with 2oz of pag oil and 2 oz of r134a mixed and just fill
like any other can apparently.
seems I have to go to walmart or ebay.
florian

On Tue, May 6, 2008 at 11:24 AM, Raimund Feussner <rfeussner@gmx.de> wrote:

> Ken,
>
> thanks for the long essay.
>
> I have to refill my Vanagon�s A/C, too (was 134 before).
>
> But, what about changing the oil when converting from R12 to R134a?
> I have to go that way on my 92 Passat.
>
> Here in Germany people freak out on A/C service, and for everyone,
> changing the oil in the system seems to be a "must".
> Get refrigerant in the supermarket? Pleeeeease, only special shops with
> environmental cerificate etc...
>
> So, my question, do you put R134 into old R12 system (with old oil)
> without any other conversions?! Just new dryer and you�re done?!
>
> Thanks
> Raimund
>
>
>
> Am 06.05.2008 20:07, Ken Wilford schrieb:
>
>  Jim,
> > I have done this conversion many, many times and at many, many different
> > levels.  When I initially started out I was really super picky about
> > changing out things and going by what the early EPA/Air Conditioning
> > sites recommended.  However time has passed and I have been in a hurry
> > with no equipment and just wanted cold air.  If you have a later model
> > Vanagon (86-91) you can go to Wal-mart buy four cans in a kit and
> > convert the van in ten minutes.  If you system is totally flat, add
> > about a can of R134a to check for leaks and then replace what ever parts
> > are needed that way.  If the system still has a little in it then it
> > probably has just leaked out over time (normal) and you can recharge it
> > and it should last a while.  Charge into the low side (S port).  If the
> > compressor doesn't want to kick in you can hot wire it and run it until
> > it picks up enough refrigerant to stay on by itself.  The biggest pain
> > is that the R134a charges really slow.  I hurry it up by putting the can
> > in some warm water while it is charging.  The whole system holds less
> > than four cans so if you charge it to that point and it still isn't
> > working (putting out cold air) then I would shut it down and figure on
> > replacing the compressor, drier, and expansion valve, blowing the hoses
> > out, putting new oil and o-rings in.  If it does put out cold air then
> > just use it until it starts losing it's charge again.  If you want to
> > find where it is seeping from if you have a slow leak you can buy R134a
> > with leak detector dye in it (it is messy though).
> >
> > I have found that about 75% of the time you can just charge the system
> > with a couple of cans and you are good to go for several months.  I
> > charge mine about twice a summer.  Cost to me is about $36 in R134a and
> > my time.  It works really well and should freeze you out of the van.
> > Whenever you turn the A/C switch on you should get the radiator fan on
> > as well at the same moment.  If this fan does not come on then you
> > should check your low speed radiator fan resistor.  This needs to
> > function if the A/C is going to work well for you.  If you have a
> > problem with speed number 3 that is usually the "evil relay number 13"
> > that is in the back of the van.  It is located on the left side of the
> > rear hatch inside the van.  If you have a camper the wiring is inside
> > the cabinet back there or if you have a passenger van there is a plastic
> > panel over these wires.  There is also a large fuse back there that can
> > blow and cause your system not to function.
> >
> > If you find that you are going to need new A/C hoses you should be able
> > to get these made up for you locally.  If not I can probably get them
> > fabricated for you here for a charge.
> > I also have new and rebuilt compressors, dryers, and expansion valves on
> > my site for sale.  Also anyone who buys their parts from me gets my
> > support over the phone for any questions they might have.
> >
> > If I have to replace something major like the compressor I will blow the
> > lines out with shop air, replace the oil with Ester oil, replace the
> > drier and expansion valve and all o-rings.  Pull a vacuum on the system
> > for about 30-40 minutes.  Then charge the system with a gauge set.
> >
> > I hope this helps you.  Let me know if you find you need anything.
> >
> > Ken Wilford
> > John 3:16
> > www.vanagain.com
> >
> >
> > Jim Felder wrote:
> >
> > > Does anyone know of a complete set of instructions for converting to
> > > 134
> > > from R12? I'm talking complete, like where to get any parts needed
> > > for the
> > > compressor and how to get the compressor open to fit them, how to get
> > > the
> > > oil out, put new oil in, and that sort of thing. I inherited a nice
> > > set of
> > > manifold gauges but have never used them. I also have access to a
> > > vacuum
> > > pump if that is required.
> > > Jim
> > >
> > >
> > >
> >