Found this:
http://www.swedishbricks.net/faq/ac.html#ventsMy middle vents are not blowing cold air, any ideas?
To: swedishbricks@me.rochester.edu
From: dlonce@www.comet.chv.va.us (Dan Lonce)
Subject: Re: A/C Problem - Middle Vents Not Cool
Date: Tue, 28 Nov 1995 18:13:16 -0500
>On my '89 760, the A/C seems to be working properly but there is a
>problem with the vents. The far left and right vents are cold, but
>the middle vents are only moderately cool to lukewarm (depending on
>how hot it is outside). This happens whether the air is being
>recirculated or not, so it appears that some hot air from outside is getting
>in.
>A mechanic suggested that maybe the heater was not shutting off
>completely as it should when the A/C is on, but it seems to me that
>this would affect all vents, not just the middle ones. I tend to
>suspect louvers which may be located in the air ducts.
>It's cool in Texas now, but it gets hot in the summer! Has anyone
>else experienced this problem? Any ideas or proposed
>solutions?
>David Grimm
>dgrimm@tcac.com
Dan Lonce
dlonce@comet.chv.va.us
Hey I talked to the guys at the dealership I work at and they said they had seen this problem once before. Beleive it or not they said that the car is a little low on freon. Don't ask why the outside vents will blow just cold but they said it took them about half a day of messing with the car to figure it out. See if your care is low on freon.
92 940 A/c Problems, heat variations from vents
May 7 2008, 10:29 PM
