[swiftknight23]

first of all, is the ac/ heater even blowing air. if not then it could be a blower, fuse, or electrical problem. but if its blowing air then its most likely the heater core,

this will answer your question on the heater control valve and give you a little background on the heater.

we can understand this diagnosis by understanding how a
standard automotive heater works.
First off, there is the "heater core". It is located behind the
dashboard vents and looks like a mini-radiator. Essentially,
the sole purpose of the heater core is to emit heat. Where
does this heat come from? Well, hot coolant from the
engine is circulated through it. The fan (a.k.a. blower) blows
air through the heater core, out the vents, and thus into the
passenger compartment.
So then, how does the heater control valve fit into all of this?
It controls the flow of coolant to the heater core. If the valve
is open, coolant will flow to the heater core and thus the fan
will blow warm air out the vents. If closed, coolant won't flow.
Hence, the air isn't warm.
It should now be clear that since this vehicle's heater blows
air that isn't warm, the heater control valve must not be
opening. This is either because the valve itself is faulty or
the device activating it is.

hope this helps

Terrell