A/C only works on setting 4 on 1993 Nissan Altima

when i got the car, setting 3 & 4 was working.
a month later now only setting 4 works. i can hear the
a/c compressor kick on when it's on setting 1,2,3. but no air is being blown out..what's the problem

Asked by for the 1993 Nissan Altima
If the fan motor only works on high then the fan motor resistor is bad and needs replacement
2 more answers
it could also be a bad fan speed switch
I agree with GetrDone, it is the resistor that have gone on positions 1 & 2. The resistor pack (which all of the resistors reside for the blower) sits next to the blower motor. Here is a link sample of the resistor pack http://www.partsgeek.com/catalog/1993/nissan/altima/climate_control/blower_motor_resistor.html.
Extremely rare for the switch goes bad.