AC Controller Q

[Steve Sherman]

Mathew:

Hi.  Thanks.  This sounds like an worthwhile thing for me to check as well.
Although I have checked for tight electrical connections, I have not tried
looking at the state of the contacts nor cleaning them.  Think I will give it a
try...

Just out of curiosity, how do you measure the voltage at the solenoid, solder in
leads that go out of the box?

Steve

Matthew Caprio wrote:

> FYI-
> I have (partially) diagnosed this same problem in my car, and it turns out
> it is related to a low voltage problem locally at the AC Programmer (the
> vacuum switch box).  I have monitored the signals to the solenoids, and they
> sometimes drop from their constantly regulated 11.75v down to 9.5v.  I think
> that the 12v to the programmer is regulated somewhere, probably the AC head
> (the box with the settings in the dash) and for some reason the supply
> voltage to it drops slightly enough for the regulator to "fall out", and
> have the output drop to this ~9v level, at which point the solenoids might
> lose their force enough to become unreliable.  In my case, when this
> happens, if I tap on the box the proper vents may again be chosen.
>
> My car system voltage is not low >13v, I have monitored it during these
> events, so I have not figured out what is causing the low voltage at the
> programmer.  Perhaps my lead to the AC head is bad, or a connection is bad
> at one of the connectors, or my head is going bad?...  I will test it more
> thoroughly in the future, and let you know what I find.
>
> In the mean time, I have installed a jumper hose arrangement to avoid my
> programmer and select my vents "manually" putting the air reliably to the
> top/center vents.
>
> Good luck.
>
> Matt
>
> ----- Original Message -----
> From: "Steve Sherman" <spsherm at attglobal.net>
> To: "quattro" <quattro at audifans.com>
> Sent: Saturday, August 11, 2001 12:31 PM
> Subject: AC Controller Q
>
> > One of my 5K's is giving me fits in trying to fix the AC Controller (the
> > vacuum switch part).  The symptoms are the usual air coming out of the
> > defrost vents when it should be at the dash vents.
> >
> > In the past (with other 5Ks) this has not been that big a deal. Yet
> > nothing I try on this car seems to work for long. I have tried a couple
> > of controller boxes (both have been checked for hose leaks internally).
> > I have checked the lines between the controller and the right vacuum
> > actuator and they are good, no leaks and they do pass air.  The vacuum
> > actuator does work (will move when vacuum is applied).
> >
> > When I work on the system I can ususally get things to work before I put
> > the under-dash back together, yet a day or two later it is back to not
> > working.  The only thing I have not  checked is the actual vacuum level
> > at the controller.  Anyone know what vacuum should be on the black
> > "input" line at idle???  However since other vacuum actuated things seem
> > to move OK (like the air recirculating door) I have been assuming that
> > the vacuum level is OK...
> >
> > Any ideas of where else to look on this one??
> >
> > TIA
> >
> >
> >