Why do you feel air blowing in Under the dash when driving and all fans are off?
Make sure your fan switch has an ‘off’ position, as some vehicles have ‘low, med, and high’ while ‘off’ is actually on the position selector…which you have to select, in these cases, to shut the fan off. In most vehicles, air will travel through the heat/vent ducts into the vehicle while driving. The movement of the vehicle forces air inside this way, even if the fan is off. HOWEVER, the selector switch would most likely have to be in the ‘heat’ or ‘floor’ position in order for air to go to the floor. If your fan switch DOES have an off position, then it is likely your vents haven’t closed off the outside air. The selector may have an ‘off’ position which will close the air inlet and block the air from entering the vehicle.
