heater problems

heater works only on the passenger side, door,floor, defrost, dash. driver side blows out cold air from door, floor, defrost, dash. what would cause half the car to blow hot air and the other half to blow cold air?

I would think it is the drivers side air mix door actuator. I just checked my old GM price list and it's listed for $95.23. So I think I would head to the junk yard.
Looks like you are not the first person to have this problem
http://www.automotiveforums.com/t214208-no_heat_on_drivers_side.html

Very common problem. 99% chance is the drivers side blend door.