When air conditioner is on air blows out of floor vents only

Hello,

It sounds like you have a faulty mode door actuator.
The mode actuator is what controls the air flow through different settings. Sometimes it can fail and just be stuck on one setting, regardless of what you select.
The actuator is located on the side of the HVAC box under the dash.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

I have attached diagrams below showing the mode actuator location and replacement procedure. This does require reprogramming of the actuator when replaced.

Note: This is for a manual HVAC system. If you have automatic climate control let me know and I will provide you with information on that.

Thank you.