Hot air will only blow out of the defrost vents (the ones in the top of the dash) and the floor vents (the ones right above the tranny tunnel). You also need to make sure the dash selector switch is working/adjusting correctly....sometimes the cables/linkage doesn't move properly and when you think it should blow through the defrost and/or floor vents, it isn't and you won't get any hot air if that happens.
It could also be that the heater core is clogged. But usually if both hoses going to it feel hot, then coolant is circulating through it properly.