Seems like little things are coming up fairly frequently on this car, a 1995 940 turbo wagon. This time, the turning the vent control dial on the climate control system doesn't control which vent the air is coming out of. Fan seems to working fine. Recent work on it was replacing evaporator by a local auto AC outfit and DIY replacement of radio suppression and fuel pump relays and the speed sensor. I don't think the DIY replacements shouldn't be related to the problem, and the AC was working fine after it was replaced. I wonder if anyone can tell how that dial works, what it is actually doing when I select the different air-flow vent paths. Also, whether it is an easy diagnosis and fix or a job for a pro. Thanks.

The selector dial controls vacuum motors which in turn open and close various ducts. Take a look at the back of the HVAC control unit to make sure the vacuum tubes are still plugged in.

Turned out that I had dislodged the vacuum line that goes into the top of the intake manifold when I worked on the car last weekend; a 1 sec fix once I found it. I learned something about removing the radio and HVAC in the process, though. Thanks for the reply.