according to the wiring diagram, you have a fusible link that goes to the heater circuit breaker. from there it goes to the heater relay.
you have a 'gauge' fuse 7.5A to the relay too.
you have two wires to the heater blower motor. one blue and red and the other just blue. with the key on turn the fan switch where it would normally on. check the blue and red wire for power. if you don't have power look at the relay, circuit breaker and fusible link. If it does have power check to see if you are getting the ground signal from the switch and blower resistor