With the engine running, does the air come out of the vents it is supposed to when you change the position of the selector switch, defrost, floor, ac vents?
If you have an ac car, the vacuum still needs to be hooked up for the controls to work even in heat mode. If the vacuum heater valve still works, no reason to remove it. If it doesn’t, but a manual one at the parts store. They are only about $5. Turn it on in the winter and off in the summer.