Dash vents not working

A vent flap actuator probably needs to be replaced. It's what moves your vent flaps from heat to A/C or to plain "vent air" when you change settings.

The discussion in the link includes vent flap actuators. Unfortunately, they also include the infamous no low speed fan problem too.

Cannot get any air from dash vents while defrost and floor vents work fine...

Your particular actuator will be a different one than they found.
They're all a absolute pain to get at because they can be well buried in the dash. I would start looking under the dash on the passenger side, that's where most of the air control is. Cannot get any air from dash vents while defrost and floor vents work fine...

usually a faulty blend door under the dash

I think your problem is the head unit that selects where the air comes out ie. Face, floor, defrost, or hi-level face and floor. If that's not working then it will not let you switch location that you want the air to come out.

Under the dash there is a vacuum control that opens and closes the doors. Door could be stuck

There is a blend door acuator which moves when u change your settings. Its a electric motor. Down under dash, Will need a mech and a heating and cooling diagram to find where the motor is,

this vehicle has electronic acuators that move the doors and do not use vacuum. the mode door actuator is bad causing this problem. there is a defrost acuator that works the defrost position and a mode door that works floor/vent operation. the defrost moves and diverts airflow up defrost vwents this is why you can still have defrost and floor.

Is it a new vehicle? I had a new vehicle that had the same problem. Answer was that the holes weren't punched out of the vent.

Sounds like you have a supply vacuum problem. When you lose supply vacuum to the control head it defaults to defrost.

the vent door is broke in the heater control box under dash