New guy with some heater questions.

Ok Y'all I have a 1974 Plymouth Duster, Ive posted some pics of my car in welcome wagon btw.

Ive been messing with my heat controls everything works, I just cant get the heater to open when its placed on heat went opens, or if I switch the red white or yellow hoses I can get the Deffrost to work but then the heat wont open or heat will open then no defrost. I have a 73 service manual but the diagrams arnt great. Any help or pics would be great! and yes its an a/c and both boxes have been rebuilt. Thank you.