A/C blower motor not working

With car running A/C engaged, compressor is engaging as well. There is no air flow into the car through the vents. No matter what speed you put it on, one through four, nothing. Checked all fuses, good. Got into dash. Disconnected the blower motor plug. Meter in place turned the key, no voltage on blue/ white striped. Left positive lead in plug and put ground to chassis ground, viola, 12.4 volts. Put temperature ground to plug, plugged back into motor. Turned key to on position, fan motor operates in "full on" (four) mode no matter what is on the selector (one through four,).
Help!