Hotter heater possible?

Yeah, my car does have a million little holes and such where air can escape. I know how to fix that; but, even when my engine is fully warmed up and I put my hand over the vents, it's not that hot. I'll try the flushing thing though. Heater coil should be good, seeing that the overall condition of everything else in the car so far has been good enough to necessitate only a mild cleaning/fixing.