ac problems 1972 c10

[bdnbfrank]

I recently purchased a 1972 c10. The a/c does not work. When you move the control to a/c the compressor tries to come on but i am getting no blower motor. I have checked the fuses of course and the are good. I tried jumping out the blower switch and no go. The blower motor works if you put power to it with a jumper wire. Where should it start looking first to get it to work. The owner says the a/c was working but the truck had not been driven in a while.

Can you guys help me?