A post from another site suggest that the 'most common cause of our Buicks' no air from mid vent problem is':
"The most common fault is a vacuum leak in the small black plastic hose that comes from the engine compartment thru the firewall an in under the dash.
Look for the vacuum line going thru the firewall and back track it into the engine compartment and you will most likely find it broken or split somewhere in the engine compartment.
Find a connection and put a vacuum gage on it, You should have full manifold vacuum."
Which mechanic had suggested but I thought it too simple a fix. However, with hot weather here. I am going in search of that little black vacuum line with a leak in it and FIX it ---especially as it will not require opening up the dash!
Will let you know what I find.
Monday, June 26th, 2006 AT 8:41 PM