heater trouble

[1970shortwide]

What's going on fellas? I got a 1970 chevrolet c10, who is giving me electrical problems. Its my daily driver and my pride and joy.......some of the time. I have bought a new engine wiring harness, a new front engine wiring harness after the old one caught fire. New starter, alternator, voltage regulator, and new battery. She is running like a champ but now since its starting to get cold I decided to try to hook my heater up. I bought a new heater core, new heater wiring harness, new heater control unit. And new vents. I have hooked everything up but the blower still doesn't turn on. I have a shop manual I bought but it does nothing for me with the wiring diagram on the heater. I don't know how the fan switch gets power and if it does how does it fit in the harness? I have replace fuses and all kinds of junk and still nothing! Please somebody help me! Any information will help. Thanks guys