HVAC is Wonky: Defrost Always On

[PappaBolt]

Every time I turn on HVAC with auto control, the defrost and floor vents are active. If I disable those vents, turn off HVAC and then turn it back on, the defrost and floor vents are active again.

Any speculation on why it’s always activated regardless of need? The additional airflow increases cabin noise and I’ve now made it a habit to turn off those vents every time.

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[SSteveEV]

The HVAC programming is just flat out terrible. I was freezing when it was set to 70* yesterday. Had to turn it to 72 for any heat to kick in even though it was 30* out and probably 50* in the cabin.

To answer more clearly, I don't know why they pick the vents they do but they typically reset the open vents each time. Seems like a needless use of the motors in those.