a/c problem

[frank250]

i got a 86 f250 and the a/c will sometimes turn on but not the main blower the i guess return by the passenger will turn on but shutoff after awile i replaced the fuse and stayed on for a little then shutoff and nothing will turn on and its making a wizzing sound and the main one i think was trying to turn on but making a screaching sound should i get a new blower or a new unit