May be but first -
The HVAC system commonly has a door motor actuator that blends the air temp. Or sometimes called a blend air door motor. (Actuator) Especially ATC or EATC systems. That motor controls the air temperature depending on operator input.
The air distribution is usually controlled by vacuum motors. If the front HVAC system looses the vacuum signal, the system defaults to blowing up through the defrosters.
Diagnose the problem before ordering parts. Make sure if there are vacuum lines to the control that vacuum is actually present in those lines when the engine is running.