Actually on the 83.5-85 (some 86) AC system with the single wire going to
the compressor (SD-508) there is nothing to stop the compressor from coming
on as soon as you turn on the switch and turn the thermostat to max.  So if
you are having a problem with the compressor clutch engaging then it is
either not enough voltage at the compressor clutch or the compressor clutch
itself is bad.  On the 86-91 Vanagons they upgraded the system to have
pressure switches that turns the compressor off if the pressure in the
system gets too low or too high.  The early ones were controlled by the
thermostat only.  So as long as you have the thermostat turned to max and
the fan switch turned on, the compressor will come on no matter what.
 Believe me I lost a compressor because a freon hose failed and the person
driving the van kept the AC on to keep her your dogs cool.  The compressor
continued to run, pumping out all of the oil in the system until the
compressor locked up, flung the belt off, and took the other belts with it.
 Almost lost the whole motor because of the fact that the old system isn't
"fail safe".

Ken

On Mon, Jul 28, 2014 at 9:03 PM, Project Pat <psdooley@verizon.net> wrote:

> You shouldn't have to jumper the switch.
> Well, yes, I guess so if you're filling with 12oz cans.
>
> I use a 30lb cylinder.  Just fill until the pressure builds high enough to
> activate the clutch.
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Jim Felder
> Sent: Monday, July 28, 2014 7:54 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: 1985 Vanagon A/C question
>
> You can jumper the wires to the clutch with 12v to force it to spin and
> take the charge.
>
> Jim
>
>
> On Mon, Jul 28, 2014 at 6:50 PM, Project Pat <psdooley@verizon.net> wrote:
>
> > Differential pressure.
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of
> > Raymond Markett
> > Sent: Monday, July 28, 2014 7:35 PM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: 1985 Vanagon A/C question
> >
> > Thanks, how do I get refrigerant in to an empty compressor if it won't
> > spin?
> >
>

--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com