would my heater controlle valve keep it from changing to hot air and only blow c

Yes the heater control valve, under the hood, can keep the heat from working if it is stuck closed as the hot coolant cant flow into the heater inside of the car. However there are more possibilities for no heat as well.

yes, this control unit in the dash, in front of you. controls the actuator at the damper under the dash at the floor switching from ac to heater core. got it?