There is a safety relief valve in the AC system, but it is the system's
last resort after its primary last resort. There is an over pressure (or
is it overtemperature?? I forget) switch in high pressure side. It shuts
off the compressor when a blockage or other problem creates too much
pressure/heat.

The "Last Resort" is a little hunk of solder in the bottom of the
receiver dryer. If temps get high enough, the little hunk of solder
melts in order to keep the refrigerant from "blowing out" a line or
other part.  I haven't lived right, so God hasn't yet granted me an AC
for my Westfalia, but I *think* the R/D is in the front on yours, which
means you may have abraded/blown a hose somewhere in yours.

This should be exciting, and may affect Christmas giving. Keep us
posted.

Developing business and guiding change since 1996,

G. Matthew Bulley
Bulley-Hewlett
Marketing & Communications
Business: www.bulley-hewlett.com
AIM = IExplain4u
Phone: +1.919.658.1278

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
Of Barry E. Muller
Sent: Monday, September 09, 2002 1:31 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Pop-hiss AC Prob

Hi Folks,

On Sunday my son and I went to the local air show for some high-speed
entertainment.  When we left, I wanted to cool down the '91 Carat as
"fast"
as possible so opened the doors, cranked the engine up and turned the AC
and
fan on max.  About a minute later I had some unanticipated
enterntainment
when I heard a pop at the rear of the cabin and hissing sound (not
unlike a
bicycle tire going flat) for about 2 minutes.  Once I assured myself
that I
really didn't have a flat I guessed that the sound I heard was my AC
system
dumping all the 134a (yes it was converted by the PO using the kit) into
the
van.  Whatever my van was leaking smelled of rubber - not burning
rubber,
but just like air that has been in a tire (thats tyre for Clive and
Andrew
;-) )

So,

A)  Amongst other things, I'm an HVAC moron, if you can, and will, help
me
with this - please feel free to break out the finger puppets.
B)  Is there a safety relief valve in these AC systems that will go, or
am I
probably looking at a blown line, hose etc. ?

TIA

Barry
1991 Vanagon "Sauna"