Heater woes

[Patch]

Okay...I bought a 1972 Blazer, and since I've owned it, the heater hasn't blown hot. I started to tear it all apart, and then noticed that the heater hose is connected to the radiator, and the water pump......now...correct me if I'm wrong, but both of those hook-ups are pressurized...no? I can put my fingers on the heater core outlets at full engine temp, and there not even warm.
The outlet on the intake manifold is plugged off....I havent seen it this way before...Is this my problem? It seems like the water has no where to go. Help!!! Thanks.......