1969 Camaro B/B air wiring question

[tork]

I am working on a 69 big block 427 Camaro, auto with factory air. I have a question about the wiring. I am wondering what wire goes to the blower motor, the orange one from the engine wire harness or there is a purple that come off the A/C wires from inside of the car through top middle of fiewall. There is a also a black wire with the purple A/C wires. It seems as the purple goes to the power of the blower motor and the black to the ground on the blower but what about the orange engine harness wire? That's for any help....tom