im stumpped!!!!!!!!

i have a 82 caprice that had a 267 v8.i took that motor out and put a brand new 305 n it.the old motor had an electrical distributor and everything else.when i put the new motor n,all the wires that i unplugged from the old engine i cut.everything else is fine but the heat wont blow, not even a sound.is there a fuse that actuates the heat to blow?what did i do wrong? i remind u that this is the second time this has happended to me when i did this last time!!thanks