Heating problem, PLEASE HELP

I have a 2001 Nissan Quest. The dial for the heating controls has 4 blower levels and all of a sudden the only one that seems to work is level 4. The lower three levels do not blow any air at all. Anyone have any ideas about what the problem is and how I might fix it? . The rear air works fine on all levels also

you need to replace the blower motor resistor located next to the blower motor, passenger side under dash.