Nissan Repair: Air conditioning/heater, blower motor, full blast

Question
Good morning.  When driving to work, my heater automatically turned to full blast, even though the setting was at low.  When I turned the heater off, the heater stayed on, yet shifted to the floor.  Is this a fuse problem?  Thank you for your help!

Answer
Ray,

Depending on your model and year it could be couple of things.  If the blower motor is stuck on I would change the blowr motor relay.  The air going from the vent to the floor is jsut due to the vacuum of the engine dissipating when you turn the engine off.