Wife tests me saying the fan is switching from cabin to floor arbitrarily. She'll switch it back, minute later bam! It switches back. What's going on?
Does she have the hvac system set to auto? If so, auto lets the car decide where to blow the air based on varying criteria. If not set to auto, it'll keep the settings at what she sets them to.
If you set a mode it should stay put. Does she set a mode and then hit Auto? That'll cause such behavior.
Which part of the equation is being run in manual? If the her is of the feminine gender, getting to decide everything is difficult.
That's ok. The combination still works. Run it in auto and the decision is made for you. Run in manual, you decide what is best. Just like marriage to a certain degree, but without the fear of spending an evening on the couch.