A/C problem
 

hey im new to this forum and this is my first project car. the car is a 1974 V8 350. when i got the car from the previous owner he had removed the entire A/C assembly, compressor, hoses, condenser, everything. im in the process of slowly reinstalling it all, and i figured the first step was to make sure my blower motor was working. I got the blower motor working, but now air just blows out of all the vents, the floor vents, and the defrost. what can i do to fix this? I figure it has something to do with a vacuum actuator somewhere, but i am lost as to where and how to fix this problem. any suggestions?