Air conditioner blows out the defrost vents

Hi and thanks for using 2CarPros.com.

It sounds like you have a problem with the mode door actuator. Take a look through this link which describes what is most likely happening.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position
https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

If you determine it is the actuator, here is a link that shows generally how they are replaced:

https://www.2carpros.com/articles/replace-blend-door-motor

Let me know if this helps.

Take care,
Joe