Re: 5000 S A/C, Cruise Control and OBC Questions

[Tony Lum <tlum@flash.net>]

At 01:24 PM 10/8/97 -0400, you wrote:
>I have a 1987 5000S wagon with the 2.2L engine, automatic.  I have three
>failures, two of which may even be related, with which I would like to
>be helped.
>
>A/C:  The ventilation system blows air through the defroster and
>footwell vents only.  If I select defrost, it will only flow from the
>defrost vents.  Selecting Econ, Bi-level or Auto have no effect on
>ventilation distribution.  I have had the programmer replaced over a
>year ago and the one year warranty on it expired (wouldn't youknow it!)
>this May.  When Auto is selected, the compresor clutch engages for a few
>seconds (less than 5) and then disengages for a about a minute or so
>before engaging and repeating the cycle.  I suspect the programmer, but
>wonder about a vacuum leak.  Nothing obviously wrong at the condenser
>core where the vacuum lines come through the firewall.
>

Sounds like a vacuum leak again.  You need a hand vacuum pump to test.  If
you remove the glovebox its easier to troubleshoot.  The bracket holding
the vacuum motor that operates the recirc/outside air door breaks easy
after the gasket on the inside door gets crooked.  There's a factory part
to fix this-just put one in this morning.  Remove the vinyl looking
multi-colored plug from the programmer and use your vacuum pump to test the
individual feeds to the vacuum actuators: red-to recirc door,
blue-floor/defrost flap, yellow-center vents flap, green-bilevel control
(partially negates the yellow line).  If no leaks, then the vacuum
solenoids themselves may be leaking.  To test, you need to remove the A/C
programmer from the car.   Disconnect the Bowden (temp control) cable by
removing the 2 screws holding the bracket to the case.  Trace the yellow
and red lines to their respective valves and apply vacuum (you may have to
shake valve assy a little).  If they leak down rapidly, then you need to
get a junky programmer and swap in the good valves which will correct the
air leaks.  BTW, your system has a diagnostic mode, just press the "Outside
TEMP" and "OFF" together, then the "WARMER" button till you're on display
channel 01-the display should read "00" which is a no faults found.

>Cruise control:  Can't set speed.  It is totally inoperative.  I can not
>tell readily if the system is turned on , but it just isn't registering
>a set speed command, or it isn't even coming on.  Is there a possible
>tie in to the ventilation system problems through the vacuum system?

Separate system with its own pump.  Check vacuum switches on foot pedals
(use hand pump again). These are combined with electrical switches, so test
these too.  Adjust/repair as necessary.  Check your brake tail lights-they
must be good or cruise will not work.  If all else is OK, most likely
culprit is in the set switch itself-gets intermittent and will not make
contact (BTDT in my '85 and '87).  Fixing the switch is difficult as its
kinda tricky to get apart.

>
>OBC:  The On Board Computer will not scroll through any function.  I can
>not even change the time on the clock.  The switch commands have no
>effect what so ever.  I suspected the switch, but I examined it and it
>is fine.  I did have a shop replace the speedometer at the same time as
>the problem occurred.  I intend to remove the gauge housing and verify
>that the OBC is connected behind the tachometer face.  Does this failure
>sound typical on Audis or is it likely just a connection problem.  If
>the OBC is shot, what are the alternatives to a $520 part from Audi?
>

Did you test the switch with a DMM?  My switch is getting
intermittent-gonna need treatment in the near future.


>There's a lot here, but I would appreciate any and all forms of advice
>from the Audi support network.
>
>Thank you.
>
>
******************************************************
Tony Lum
Fremont, California U.S.A

Audi Owner/Operator/Mechanic by Necessity ;-)

1987 5000S Turbo Quattro
1985 4000CS Quattro
1980 5000S Sedan
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