Date: Sat, 1 Oct 2016 09:39:26 -0500
Reply-To: John Rodgers <jrodgers113@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <jrodgers113@GMAIL.COM>
Subject: Re: 1991 Carat AC System servicing Failed trinary switch
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Dennis, thanks. I am becoming more enlightened every day on this system. I
found some good stuff on the fucnction of the trinary switch on the
internet. That helped too.
I understand about working behind someone. I once had a Cessa 195 - a large
single engine airplane. Had an oil leak in the nose cone of the engine and
it had to be removed. Took it to a large reputable shop. Thought they could
handle it. I opted to completely replace that nose piece with a rebuilt and
certified one ( you don't much put anything on an airplane that's not
certified by an approved overhaul facility). That nose cone housed the cam,
lifters and some other stuff. Very important part. A hot valve timing
check was supposed to be performed to ensure cam timing was correct. It
didn't get done, but the engine was signed off as airworthy and given back
to me. It was unsafe to fly. A dispute ensued, and ultimately I found
myself having to redo the job.(I was licensed at the time but a hanger is
really needed for the job and I was a PHS employee at the time so I gave
the job to the shop) I demonstrated to the FAA that the engine was
certified Airworthy, yet was out of time. That's such a safety item on an
airplane they went balistic. Suspended the shops operating license for 6
months. That would never have happened had they been willing to redo the
job and pull that nosecone and set the cam right. Thats a big task and they
didn't want to do it. So the dispute could not be resolved amicably, and I
wound up doing it in the Alaska winter, under a makeshift tent, in the
open, up on a step ladder, with kerosene space heaters running full bore,
but I got it right. I had learned to operate under those conditions from
one of the best in Alaska - a master mechanic and Aircraft Inspector by the
name of Bob Marvin.
These kinds of events of half-done work have plagued me for a lifetime.
Even on this current Carat project I'm finding little things left undone
that should have been taken care of during the engine change. The engine
is fine, and was done by a master mechanic, but his helpers left
something to be desired. I find little stuff: a bracket loose, a nut
missing, some external not torqued sufficiently. But I'll get there. I'm a
bit like a snapping turtle - I don't generally let go on something 'til it
thunders. Just my way. Whatever it is, it's got to be right. Aviation
training I guess. You can't park a flying machine on a cloud when something
goes wrong!
John
On Oct 1, 2016 08:46, "Dennis Haynes" <d23haynes57@hotmail.com> wrote:
>
> John,
> Getting back to that switch. Its job is to sense the pressure conditions
in the refrigerant system. As such it has to be connected to and able to
contain the system pressures. That Schrader valve is there to allow for the
switch to be replaced with minimal loss to the system. It has to be opened
when the switch is in place. That is how it works.
>
> For it to blow at some point it was exposed to excessive pressure. You
would wouldn’t be the first to have the compressor energize when it
shouldn’t. It is possible for a wiring error or defect (including part) to
back feed and engage the compressor when the radiator called for the
cooling fan. BTDT. One of the things that adds to service costs is when one
has to back track and figure out what was changed in the past. It all takes
time.
>
> As for the shop rates those are fairly typical. Here in New York
$140/hour is becoming common. What I find amazing down south is how many
techs work for so little. A lot of earn while they learn and turn over
between shops is amazing. To be honest, real business paying rent,
insurance, whatever these rates are needed.
>
> Over the years I have been involved following others work many a time.
One of my favorites was a Syncro transmission in 4 boxes sent to me from a
chain transmission shop. A lot of stuff was busted since they did not know
the disassembly steps. Wiring modifications or poor work is next big
bugaboo. In all fairness, a good AC tech and an electrical guy is needed to
figure out what is wrong now. Some time is going to be needed to test
everything out point to point and completely diagnose the mechanical-fluid
parts of your system. Every component including the expansion valve has to
be proved out. Flushing the system should have moved stuff and it is common
for the expansion valve to get clogged. You have some work here.
>
> Dennis
>
>
> From: John Rodgers [mailto:jrodgers113@gmail.com]
> Sent: Friday, September 30, 2016 5:32 PM
> To: Dennis Haynes <d23haynes57@hotmail.com>
> Cc: vanagon@gerry.vanagon.com
> Subject: Re: 1991 Carat AC System servicing
>
>
> Dennis, All:
>
> I don't mind criticism at all. Feel free to criticize as much as you
like, as much as you feel necessary. It's how I learn.
>
> I've worked on airplanes with way more complicated systems than a
Vanagon, both mechanically and electrically. Some with pressure systems
with operating pressures well over 2000 psi. Don't want to make a mistake
there. On this, I want to learn inside and out.
>
> I find that most times when I try to engage a shop in my area, I get a
flat "No" or blank stares and a "Duh!", with the exception of one, which
seems to have it's cr*p together, but they work mostly on Maserati's and
the like, and shop rates are $115/hr, which needless to say, as a retiree
in the south, that's pretty stiff! And even at that, sometimes they learn
on your vehicle. But at least they have an educated mechanical sense backed
by lots of experience.
>
> But even so, I have need to do most of my own work, or at least have
enough knowledge to be able to direct work, or as I have so many times, be
able to tell when work has gone off in the wrong direction and get that
direction changed.
>
> So, on with this AC thing, and I hope I'm smart enough to learn and not
blow myself up or get hurt in the process.
>
> Regards,
>
> John
>
> On Sep 7, 2016 22:19, "Dennis Haynes" <d23haynes57@hotmail.com<mailto:
d23haynes57@hotmail.com>> wrote:
> If you blew up an AC hose then the compressor must have been turning.
I'll apologize up front for being a bit critical but it is time you stop
trying to piece meal stuff and get the vehicle to an AC guy that knows what
they are doing and say fix it.
>
> For the wiring there are a number of places where things can fail
including the harness in the AC duct work especially if you have the
controls in the overhead duct. Some of the relays are complicated. The
system requires someone that knows how to diagnose electrical stuff and get
all that working even before playing with the refrigerant.
>
> A good AC would charge the system with nitrogen to test for leaks and
also see if the pressure switches work enough to at least get the system
started.
>
> Dennis
>
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com<mailto:
vanagon@gerry.vanagon.com>] On Behalf Of John Rodgers
> Sent: Wednesday, September 7, 2016 10:12 PM
> To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
> Subject: 1991 Carat AC System servicing
>
> Today was an interesting day of days.
>
> Flushed system, pulled a vacuum, put in PAG 46 oil, added 12 oz. Of
refrigerant, expecting the compressor to turn on. It did not! Shut down and
started sleuthing. First tested the clutch - found it to be dead. Won't
even click. Checked the AC switch - no power to it. Pulled and tested all
pertinent fuses. Pulled and tested pertinent relays except two: 2nd and
3rd stage radiator cooling fan items 10 and 11 on Bentley drawing page
> 87.3! Could not find them per the drawing.
>
> Compressor clutch relay 9 needs to be rechecked.
>
> On driving to a mechanic, a loud 'POP' was heard in thecrear follwed
byban extended shusssssssssssss sound. I stop in a parking lot, opened the
rear hatch and could still hear the soundnow coming from the left 'D'
pillar. I could feel air movement, thenfound wherevit came from. A rubber
coated device with two wires and a plug on it screwed into what appeared to
be a high pressure line had ruptured, and I lost the refrigerant. I have no
idea what that is nor what it does, besides leak gas. Can any one tell me.
I need to order parts.
>
> I still need help in that the radiator/condensor fan will not turn on
when the AC switch is turned on.
>
> Thanks for any input.
>
> John
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