Weird A/C behavior

Sun Aug 18 16:01:18 EDT 2002

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All those drawings you mentioned are of the heater core/fan housing,
Doyt.  You can only get to that from under the hood.

If you study the pix opposite of 87.128  (ie:  87.127), that illustrates
(sort of) the various separate elements.  The upper left item (air
recirculation servo) is inside the evaporator box (the thing under the rain
diverter in front of the passenger that shares its door with the door into
the cabin).  The center vent servo and the defrost/footwell servo are both
located inside the cabin at the front of the heater core/fan housing, I
believe.  At least that's where the tubes from the HVAC controller box (the
thing in the upper right of the pix that's tucked into the passenger
footwell ) go.  The vacuum reservoir is that blue thing you see in the
front of the driver doorjamb (tucked into the back of the front
fender).  The check valve (someone recently reported) is in a tube in the
area in front of the hydraulics reservoir.  The heater valve, of course, is
in front of the firewall near the back of the engine and has a coolant hose
running through the firewall to the heater core connection.

Now, if you look at pix 87.168,  you'll see how the cable from the
controller box operates the heater core temperature control flaps.  Note
that these flaps determine whether the air goes over the heater core or
not, not whether the air goes to the dash or the footwells.  The latter,
again, I think is controlled by the vacuum motors at the front of the box
that are accessible behind the radio.

At 10:57 AM 08/18/2002 -0400, Doyt W. Echelberger wrote:

>Hello Paul......I just got home from a long trip and have some additional
>peculiar A/C behavior to report.
>
>Bentley indicates that the dash vents are programmed to be closed on
>AUTO-HIGH explains why they don't blow when I expect them to.  I'm going
>to keep the fan speed setting on LOW when I use AUTO, and see if the
>center vents come on any sooner.
>
>There is a discrepancy between what the system is designed to do according
>to Bentley, and what it does in my 15 year old car.
>
>On my trip, I had the system set at AUTO-HIGH, and after about an hour of
>driving it was blowing cold air through the dash vents. And that isn't
>suppose to happen.  When I shut the engine down at a rest stop and
>restarted it, the dash vents stayed closed at the same setting for another
>hour, and then opened up....although not all the way. It was like it was
>set on BI-LEVEL.
>
>Getting to a solution.....Eric Kissel reports that he placed a zip tie to
>keep the dash vents open. (I'm uninformed about where all these flaps are
>located and accessed.)
>
>My 86-88 5k Bentley shows a diagram at 87.128  and another at 87.174  and
>87.175
>
>I'm considering the zip tie solution, and I am wondering if I should be
>reclining upside down under the dash in the passenger front, or peering
>down into the air conditioner bay from the outside of the car, with the
>plastic rain shield cover off, to do the zip tie trick. Need some basic
>direction.
>
>Thought you might be interested in how this is developing.
>
>Doyt Echelberger
>87 5ktq in Ohio   USA
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
>At 08:26 AM 8/16/2002 -0400, Kneale wrote:
>That vacuum servo in the evaporator box only adjusts the amount of air
>going into the HVAC system from either outside or inside the cabin.  I
>suppose if the vacuum leaked there, it could reduce vacuum available to
>run the other parts of the system.  But if the servo is just moving itself
>because it's detached, I wouldn't think it would have any effect on which
>course the air took subsequently in the system.  That's managed by the
>heater core box flap controls and the servo motors under the dash behind
>the radio, I think.
>
>At 07:16 AM 08/16/2002 -0400, Doyt W. Echelberger wrote:
>
>When I took a few hours to clean out the leaves (by opening the under-dash
>hinged door behind the glove box) I found the hose to the vacuum solenoid
>disconnected and dangling, and the solenoid was loose in it's plastic
>support cage. I used epoxy to attach the solenoid to it's cage and to hold
>the hose to the solenoid. This fix didn't change anything in the way it
>worked, so I'm going to go back under with a flashlight and see if I have
>any new insights while upside down, curled up like a pretzel. And I'll try
>the "Econ" and letting up on the throttle trick. Be assured, you will all
>hear of any success.
>
>Let's stay with this until we get it working right.  Thankfully, the
>default position does cool the cabin fairly well on my car, most of the time.
>
>Doyt Echelberger
>87 5ktq in hot and humid Ohio
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>At 05:09 AM 8/16/2002 -0400, Larry Leung wrote:
>Paul, Doyt,
>
>I have a combination of your problems. I have the ability to get cooled
>air through the dash vents,
>but after awhile it blows out the defroster and floor (though not too
>strongly). I have found two things
>restore things to the dash (basically Paul's trick, turn the CC to ECON,
>back off the throttle (raise the
>vacuum), air out the dash vents again, turn back to A/C), or raise the
>set temperature to the point the
>fan doesn't run at full speed. I BELIEVE that it's a vacuum problem,
>however I have yet to trace all the
>leaks in the car's system (i.e. I don't quite pass the dipstick test) so
>I'm not sure. Perhaps it's a leaking
>servo under the dash. The problem is it's WAY too hot to work on the car,
>especially under the dash
>under the greenhouse in the hot sun. Ugh. Anyone have any other ideas?
>
>LL - NY       l.leung at juno.com
>
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
> > Date: Thu, 15 Aug 2002 22:38:31 -0400
> > To: "Paul R. Luevano" <paul at clarity.net>
> > From: "Doyt W. Echelberger" <Doyt at buckeye-express.com>
> > Subject: Re: Weird AC Behavior
> > Cc: quattro at audifans.com
> >
> > Paul, it does my heart good to read your story.  The A/C of my 87
> > 5ktq has
> > been doing that with increasing frequency for the past two years.
> > This
> > summer it has gotten to where it almost never blows out the dash
> > vents when
> > set on "Auto."
>.......................snip.............................
> > Check out Scott's stuff at the address below and let me know if you
> > can
> > make yours work.
> >
> > http://www.sjmautotechnik.com/AC.html#recirc
> >
>
> >Doyt at buckeye-express.com>
>
> >  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> > At 08:45 PM 8/15/2002 -0400, Paul wrote wrote:
> > >OK, so it has been hot .............snip...............
> > >
> > >Over the last few days, I have observed a very weird occurrence.
> > When set to
> > >"Auto" the AC will stop blowing from the dash vents.  This can
> > happen after
> > >several minutes or after just a few seconds.  It seems to blow out
> > of the
> > >defrost vents, but very weakly. Here is the weird part, if I switch
> > it to
> > >"Econ", it blows out of the dash vents with a vengeance.  I can
> > then
> > >switch back
> > >to "Auto" and it will repeat, lasting from several seconds to
> > several minutes.
> >                       paul at clarity.net
>
>
>
>
>
>
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