More AC - 90 CQ

[Max Baker]

Thanks for all the help guys.  Paul and Wylie both emailed me off-list w/
some good diag ideas that worked.  I got another chance to check this out.

I used the diag mode of the automatic climate control system I hate so
much, and these most excellent documents : http://20v.org/climate.htm
and http://20v.org/climate2.htm#D8-40

and found (w/ the help of a co-driver) that the reason it was cycling was
because of:
    Segment 5 lights up
    Compressor off. A/C refrigerant low-pressure switch open.

So it does look like I'm just low on coolant.  I'll use ya'll suggestions
from the other thread to address that issue.

Cheers,
-m

On Tue, Jul 01, 2008 at 05:35:21PM -0400, Ameer Antar wrote:
> Sounds like it could be a high pressure switch or blockage of the expansion
> valve. I would check the high/low pressure switches and wiring. Then some
> pressure checks are in order. If there is some partial blockage in the
> system, too much pressure will build up and then the switch will disengage
> the clutch. The pressure goes down, the system resets and then cycles over
> and over. The blockage is usually in the expansion valve as there is a
> screen in there to protect the valve.
> 
> -Ameer
> **
> 
> > Message: 7
> > Date: Tue, 1 Jul 2008 09:37:58 -0700
> > From: Max Baker <max at warped.org>
> > Subject: More AC - 90 CQ
> > To: quattro at audifans.com
> > Message-ID: <20080701163758.GA21717 at warped.org>
> > Content-Type: text/plain; charset=us-ascii
> >
> > Hi List,
> >
> > As long as we're on AC problems here, I've got a 1990 CQ with the AC
> > Delco-style automatic climate controls.
> >
> > The problem I'm having is that the AC cycles on and off at about a 45
> > second period.  I set the controls to auto/LO/fan high and rev'd the
> > motor.   I can see the clutch on the AC compressor coming on and off at
> > the 45-second interval.  It's very annoying while driving because the car
> > lurches a little every time the compressor comes back.
> >
> > I'm hoping it's just low on coolant and I can find some R12, but does
> > anyone have any other ideas?   I still haven't found a Bentley for this
> > car, so I don't have the factory service checklist for this AC system.
> >
> > Thanks!
> > -m
> >
> >
> > ------------------------------
> >