If the fan (Blower Motor) is not working, you will not have air flow to any mode selection (floor,vent,defrost). Power source problem could result in the blower not working, as could a resistor or blower motor failure.
the fan switch itself has a high failure rate on that car. If you do not have the ability to perform the needed testing to pinpoint the problem you may want to try a switch- they are cheap and easy to replace. Greg