* Ventilation mode selector: The most common reason is that the ventilation system is set to "floor" or "feet" mode. Check the controls in your car (buttons, dials, or screen) to see if it's accidentally set to this mode. Look for symbols that represent feet, a downward arrow, or similar.
* Faulty blend door actuator: This is a small motor that controls the direction of the airflow. If it's broken or jammed, it might be stuck in the "feet" position. This often requires professional repair.
* Vacuum leak (in older vehicles): Older cars sometimes use vacuum lines to control the airflow. A leak in these lines can prevent the system from directing air to the vents correctly.
* Electrical issue: A problem with the wiring or control unit could also be causing the problem.
* Blocked vents: While less likely to affect *all* vents leading to the dash and windshield, a clog in the vents themselves could prevent air from coming out anywhere but the floor.
To troubleshoot, start by checking the ventilation controls. If that doesn't solve the problem, you'll likely need a mechanic to diagnose and repair the issue.
