AC out defrost vent only on HIGH.

[Alex Kowalski]

The vaccum servos inside the AC programmer are suspect, in my opinion.  The
rest of the circuitry on the board in the AC programmer (behind the dash)
seems to be pretty well thought out, but as much as I hate to say this to
you I wonder if you've got a marginal vacuum servo in there, causing the
thing to go into defrost mode sporadically.

I say this because the system defaults to defrost.  You should be able to
test each one of the multicolored lines leading to the various vacuum
diaphragms with a Mityvac.  Then you can rule out that the vent diaphragms
are acting up.  After that, there are two possibilities:  either the vacuum
solenoids in the A/C programmer are marginal, or something is wrong with the
head unit.  Since it's not reporting any codes, I'm thinking it's one of the
chintzy vaccum solenoids inside the programmer that's acting up on you.

I wish someone would supply replacements for those vacuum solenoids.  They
are really pieces of crap, and if we had a reliable source of spares the AC
systems on these cars could be kept running without much trouble.

Alex


On 7/19/06, Ron Wainwright <ron_01056 at yahoo.com> wrote:
>
>
> Alex, No there are no codes..Channel 7 is good. Just
> may be a vacume leak on one of the lines comming from
> the programer to the servos?? Could be the CC head as
> well, just don't want to throw anymore parts at it if
> I don't have to..even though I do have a few spair CC
> heads & servos & such.
> I got V8 stuff to do & building that stroker
> motor..so time spent on this takes away from other
> stuff.
> Thanx
> Ron
> 90 80q 2.6l 20vt stroker project
> 90 v8q 3.6 not stock
> 93 v8q 4.2 "The Green Monster"
>
> --- Alex Kowalski <hypereutectic1 at gmail.com> wrote:
>
> > Ron wrote:
> >
> > >So anyone want top stop me & tell me otherwise??
> > >Thanx
> >
> > The only thing that I remember is that the climate
> > control defaults to the
> > "defrost" setting when there is a system fault,
> > which *should* be registered
> > by the head unit.  Have you checked the codes on the
> > existing AC head unit
> > and watched the graphic as this weird behavior
> > happens?  It sounds like the
> > head unit is flaky, but it would be nice to see if
> > it's reporting any codes
> > before you replace it.  I can help with that if you
> > email off-list.
> >
> > Cheers,
> > Alex Kowalski
> > '87 5KCSTQ
> > '86 5KCSTQ
> >
>
>
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