540guy

just pulled my ac and dash.on the passenger side of the car the ac lines run to the firewall and then inside and into a black box that is mated to what i think is the heater core.(has the vents on it for winshield defroster).when i removed this "black box" it had a fan and a mini radiator.a large area of the heater core was just left open.do i need to fun this ac(black box) or will my heat not work????????
will post pics if needed