I did some preliminary poking around with the a/c compressor yesterday. I
tried to jumper it using the wires coming out from behind the clutch to see
if it would even turn on. I can manually turn the clutch so it doesn't seem
locked up but the compressor did not make a peep. My system was never
converted from R12 and a friend who is familiar with a/c has a manifold
set. We hooked it up and there was 0 pressure in the system. So based on
Dennis' advice I presume I will need at least a new dryer and perhaps an
expansion valve because of potential moisture intrusion (its been many
years since it was used). Jack R on the list also recommended new hoses. Do
you think that the compressor should have turned on after I tried to jumper
it?
Thanks
Rick

On Sat, Jun 13, 2020 at 10:54 AM Dennis Haynes <d23haynes57@hotmail.com>
wrote:

> Some thoughts for AC repairs.
> Of course we all want low cost easy fixes. Often they will increase cost
> at later dates.
> If looking to do it yourself consider doing some research and more
> importantly get some tools. Legal and environmental stuff aside, with a set
> of service gauges and a vacuum pump you will be able to diagnose properly
> fil the system. When converting to r-134a you want to get goo conversion
> fittings. Not the cheap die-cast crap. For the late campers you will need
> to access the high pressure service port in the cabinet. Some disassembly
> of the cabinet required.
>
> Almost all automotive AC systems leak at some rate. The compressor seal is
> the obvious given. Periodic testing and topping off is required
> maintenance, not servicing after it stops cooling.
> As refrigerant leaks out, magic occurs and moisture laden air gets in.
> During part load operation, (closing expansion valve) it is common for the
> low pressure side to actually go into suction. This is made worse by a
> system low of refrigerant and the Vanagon adds to it with the compressor
> run at those higher engine speeds.
>
> The filter dryer has a desiccant element to deal with some of the moisture
> that will get in. It can only hold so much and a very limited amount will
> leave during evacuation. Replacing it is part of any significant service
> activity.
>
> Moisture in the system does a number of bad things. First it will cause
> corrosion. Next as it increases operating pressures and reduces efficiency.
> Finally, it can cause ice crystal to form especially near the expansion
> valve and some times even blocking. An expansion valve blockage can
> immediately destroy  parts such as hoses and the compressor before the over
> pressure switch (if equipped) can react and try to turn the compressor off.
> Blown hoses, exploded switches, and yes busted compressors are often caused
> by this.  Unfortunately after the event the ice is gone and most do not
> understand what happened.
>
> The Vanagon AC system has a lot of excess room for refrigerant due to the
> layout and length of hoses. It will work even significantly overfilled.
> However, especially with R134a you really need to fill it by volume. So for
> normal service, recover and evacuate. Weighing what came out will give an
> idea of leak rate and refill by weight. 1,300 to 1,400 grams seems to work
> best and allow for some leakage and continued operation. Overfilling really
> increases the HP consumption especially at high engine speeds. Compressor
> starving at high speed is part of the controlling high side pressure and
> power loss. If you hear the fan speed kick up at highway speed you are
> possibly overcharged.
>
> Hope this helps,
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List <vanagon@gerry.vanagon.com> On Behalf Of
> Richard Koller
> Sent: Friday, June 12, 2020 2:50 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: A/C
>
> Ok guys thanks
>
> On Fri, Jun 12, 2020 at 12:32 PM kenneth wilford (Van-Again) <
> kenwilfy@comcast.net> wrote:
>
> > I have had good luck just charging it with R134a until the low side is
> > seeing 40 psi.  You want to be sure your low speed fan is coming on
> > when you turn on your system to prevent the pressure getting too high.
> >
> > Ken
> >
> > On Fri, Jun 12, 2020 at 12:17 PM Richard Koller <brvkoller@gmail.com>
> > wrote:
> >
> >> Hi all,
> >> My A/C has not been used in many years and I was going to attempt to
> >> recharge it to see if it works. Is this the wise thing to do? Or
> >> should it just be evacuated and recharged? It worked fine last time
> >> it was used. It leaked down so the compressor won't start.
> >> Rick
> >>
> >
> >
> > --
> > Thanks,
> > Ken Wilford
> > John 3:16
> > https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.v
> > anagain.com
> %2F&amp;data=02%7C01%7C%7C83f408d63bc4478ba14208d80f017268%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637275846168598892&amp;sdata=96PyUGERzkmmX3Ix75DkrJLsIyRKgluEbaxnBaHl94k%3D&amp;reserved=0
> >
>