Date: Fri, 26 Jul 2002 00:08:21 GMT From: "Jim Moore" <jmoore3nopsamhlink.net> Subject: Re: AC Question, 97, 900S
"Harry Feinberg" <modern_1nopsametcom.com> wrote in message news:ahnu6r$aku$1nopsam.atl.mindspring.net... > I have 1997 900S, the AC works properly most of the time. As a preface I > must say that I've had perpetual problems w/ the AC since day one. Anyway, > here's the scenario, I'm driving along w/ the AC on & cabin blower in pos. > 1, 2, or 3, or 4. I will notice a constrictiion and a whirling noise (like > putting a piece of cardboard n front of a fan), the airflow comming out of > the vents is now almost nil. I then turn the AC compressor off, and wait > 30-60 secounds. Like magic the constriction goes away, I turn the AC back > on, until it happens again. Typicaly a few minutes later. Same process seems > to revive it. This behavior tends to occur after highway driving for more > than 45 minutes. > > What do you folks think, is there some sort of vacuum leak I can check? Is a > solenoid closing prematurely? > Are there other aspects ofthe motor that might influeence behavior like > this, any possiblity that a vacuum line might be mis-routed. Any advice is > welcome. Thanks in advance. > > Harry > Guilford, CT > Sounds like the evaporator is icing up. Possibly a faulty icing switch. This is essentialy a "pre-set" thermostat mounted on the r.h. end of the evaporator. They are actually adjustable, by turning a small screw on the switch, although I'm sure the folks at Saab don't recommend that. On my 1995 900S (manual a/c), I've adjusted mine slightly lower to allow the compressor to run longer due to what I consider a marginala/c system overall. If this has always been an issue with your car, you might be able to adjust this thermoswitch to cut-out at a slightly higher temp. If this condition came about suddenly, I would suspect the switch has failed. This switch can be accessed by removing the plastic cover from the r.h. end of the evaporator housing, after removing the glovebox. It is a somewhat delicate procedure; take it to your mechanic if your not comfortable with doing it. Jim Groveland, MA
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