I have searched quite extensively and not found this issue here. I had to replace my Blower Motor Controller and did so with the aftermarket harness upgrade. Since doing this (a couple of weeks ago) I have had this happen twice... with my HVAC turned OFF completely, it still blows air. Not out the vents, but it seems to be behind the dash. The fan switch does nothing, the OFF button shuts off the head display, but no change in air. And the AUTO button changes nothing with the air either. The only way I have found to turn it off, is the turn the car off. Then it's fine. Anything from the experts?