Is there any way to force air out of the dash vents (the ones that can be directed on the driver/passenger) in a 98 DeVille? I cannot seem to do anything manually with the vents. The car puts the air where it wants. I can force it to defrost with the button but nothing else!

You need to pull the DTC's from your car's built-in reader-scanner system. It sounds as if a blend or mode door is hung up. If so, it will set a code so you can begin diagnostics.

The Deville did not get a mode control button until 2000. On the pre 2000's heat comes from the floor, cooling from the dash vents and never the twain shall meet. That was always a pet peeve of mine.

The Deville did not get a mode control button until 2000. On the pre 2000's heat comes from the floor, cooling from the dash vents and never the twain shall meet. That was always a pet peeve of mine.

Savages!