When selecting either air, heat,vent etc. air will come out either from the floor or dashbaord or the defrost vents. It will switch from one to the other on its own.
Any suggestions?
Thanks for your help
If you have automatic climate control (digital readout), then it is supposed to choose where the air comes out for you. (and is working correctly)
If you you don’t, and the outflow is changing without you changing the control, then you probably have a vacuum problem somewhere. (The expected change would be to switch from where it is supposed to come out to the defrost outlets instead.) Check for vacuum leaks or a faulty vacuum check valve.