Date:         Sat, 4 Oct 2008 10:18:57 -0700
Reply-To:     Keith Hughes <keithahughes@QWEST.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Keith Hughes <keithahughes@QWEST.NET>
Subject:      Re: vanagon Digest - 3 Oct 2008 - Special issue (#2008-1075)
In-Reply-To:  <20081004020924.C203F244C03@mpls-mf-05.inet.qwest.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

> Date:    Fri, 3 Oct 2008 16:54:04 -0700
> From:    JAIME E FORERO <jforero@SBCGLOBAL.NET>
> Subject: AC does loses freon
>
> Hi, my 91 Vanagon's AC has been giving me the fits for a few years now.  Every spring I have to get it loaded with freon.  This year I had my mechanic take the evaporator down, he changed the expansion valve, put it  rebuilt compressor and fixed a very small leak in the system. The charge is again low and I don't know what to do because we have checked all joints and there is no evidence of a leak using a leak detector.  Obviously the freon is leaking somewhere.  R12 was the original fluid but since we can't get it anymore he uses something called Freeze 12 which works OK but does not cool like R12.  Any suggestions, hints, advise???
> Cheers
> Jaime
Jaime,

You're looking at 8 fittings, evaporator, condenser, TXV, 2 service
ports, about 35 feet of hose, and a compressor shaft seal, all of which
can leak.  At each fitting, you have both the fitting-to-hose crimp -
most of which are likely leaking to *some* degree after all these years
- and the o-ring to device (compressor, drier, condenser, evaporator)
seal which can also leak.  So, you can expect that you'll lose some
charge every year, and if it's in the 1 pound or so range, you'll likely
never find it with a leak detector.  You can go with the UV dye approach
(i.e. Freeze-12 with dye), but that introduces another material into the
system that reduces cooling efficiency - especially if you don't know
whether it's been used before.  The dye is not as volatile as the
Freeze-12, so it stays behind when the Freeze-12 leaks out.  A couple of
potential issues with Freeze-12; it is a blend of R-134A and R142b, and
the components *can* leak out at different rates, so as you keep
'topping' the system off with additional Freeze-12, the concentrations
of the components can change, affecting cooling.  Always best, when
using a blend, to evacuate the system and recharge when you need to add
refrigerant.  Secondly, R142b can degrade nitrile o-rings and seals
(sorry, but I don't know whether any nitrile was used in the Vanagon or
not).  That said, I've used Freeze-12 in the past (in a Golf), and it
worked quite well.

You basically have 2 options; 1) live with it the way it is, 2) replace
all of the hoses and the receiver/drier (always, always, always replace
the receiver/drier when you have to break into the system - they are
cheap, the dessicant does degrade and lose effectiveness over time, and
they are basically where most of the crap in the system goes to hang
out).  Please do NOT consider any "stop-leak" products, as they will do
more long term harm than any short time good (if they work at all).  You
also absolutely DO NOT want to convert to R-134A and PAG or Ester oil,
*without* fully flushing the system, hoping to create some sort of
'sludge' to seal the hoses - that way lies madness.  You probably don't
want to replace that compressor AGAIN do you?  If you go the route of
replacing the hoses (and all hoses sold today are barrier hoses as far
as I've seen) you can stick with Freeze-12, or you can convert to
R-134A.  If you live in a very hot climate (like here in Phoenix) you
likely won't be happy with the R-134A performance unless you upgrade
your condenser to a more efficient parallel flow style, such as all
R-134A designed systems use.  I recently converted to R-134 on my '86
Westy with the existing hoses and condenser, and it was pretty pitiful
for performance (it was 112-115°F here at the time), so I went ahead and
did the whole upgrade with all new hoses, condenser, and receiver/drier
and the cost was about $275 for parts and R-134A.  I had a local A/C
(they're on the web at ACkits.com) shop fab the hoses for me, just took
in the old ones, and they copied them.  For a point of reference, the
shop told me they would have charged about $1200 for labor if I had
wanted them to do it.

Whichever way you go, make sure you use the A/C once a month or so to
keep the compressor oiled and the seals wet.  Letting it set idle for 6+
months really cuts down on compressor life.

Keith Hughes
'86 Westy Tiico (Marvin)