How can I fix the vent on a 2001 Saab stationwagon ( 9- 5 model _ so that it does not blow outside cold air on driver foot while rest of heating vents seem to work properly?

Easy fix: just put duct tape over it.

I thought of this too, but it seems a little generic and does not solve the question of why is it happening because usually systems heat or do not heat….ie work or do not work. It would seem easily corrected by a dial adjustment but the obvious ones are not doing the trick. Also it would seem somehow related to the defroster which on that side is also not working properly.

You have a switch or a knob to move that closes the vent for you. look for it, it should be there. If you can’t find it call your nearest Saab dealer and ask them.