Your AC control unit is working over time. It is the little
black box on the C-piller. It is nothing more than a relay that
is controlled by the dial on the dash, (a variable resistor) and
a thermistor located in the evaporator. This system works great
when working, but expensive the fix. You can by pass it by using
a switch in place of the relay contacts. Been there done that.

            Eric                   86-VW4x4
            vw4x4@fyi.net          72-240z
            Pittsburgh, PA USA     1936-Chrysler

On Mon, 27 Jul 1998, Budd Premack wrote:

> The a/c on my 86 Syncro GL (non-Westy) was inoperative when I purchased it
> two years ago.  Two weeks ago it was reborn with several hose repairs, a
> new receiver dryer and an infusion of 134A refrigerant and special ester
> (sp?) oil.  It works great, but....
>
> With the temp control knob on the warmest setting, the air is really cold,
> and does not feel any colder if the knob is turned to a "colder" setting.
> (Sorry,  I have not checked it with an accurate thermometer.)  After about
> 45-60 minutes the air gets warmer until it seems as if the a/c is no longer
> operating.  If the van is parked for 30-60 minutes, there is a puddle under
> the right side of the rear bumper (water from the drain hose).  Upon
> restarting, the a/c works fine again.  I have not had the opportunity to
> run it through several consecutive on and off 60 minute cycles as I have
> not had any all day trips this past two weeks.  It does seem as if there is
> a longer period of proper operation if the humidity is lower and/or the
> ambient air temperature is lower.  Naturally, these conditions would put
> less demand upon the a/c system.  On a nightime 90 minute drive at 75 F
> ambient, the a/c was so cold, even at the lowest fan and temp setting, that
> we mostly closed the front a/c air vents.  This was with only two front
> seat occupants, and the rear vents all closed.
>
> Note to all of you sweltering down South:  I am not complaining about being
> too cool, just making a statement to aid in problem diagnosis.  Besides,
> you don't really want to trade your winters for those in Minnesota.
>
> It seems to me that the system may be running at maximum cold capacity and
> then freezing up.  What is the problem?  Is it a bad temperature control
> switch, a/c thermostadt or capillary tube, expansion valve, or ?  The top
> and side pillar housings  were not removed, so the evaporator, expansion
> valve, relays, etc. have not been physically examined.
>
> All suggestions will be shared with my ace mechanic, who seems quite
> capable with a/c systems and Vanagons.  (He went on vacation after fixing
> my a/c, but will be back soon.)
>
> Thanks in advance.
>
>
> Budd Premack
> 86 Syncro, 73 Super
> Minneapolis, MN (Land of Sky-Blue Waters)
>