I have a 2001 chevy malibu 3.1 V6 and the air is blowing out of defrost dash and the floor at the same time any ideas of why this is happening

Broken vacuum line. Usually breaks on the passenger side. Small black tube.

Which vents, floor--defrost--dash? Can you hear the blower motor running? The squirrel cage could have broken loose from blower motor? There could be an actuator problem under the dash? If actuators are vacuum controlled and vacuum is lost, it might default to defrost, only blow out defrost vents.

have you been messing around in the dash at all? usally this happens when a vacume line in the dash to the vent control system gets disconnected typically its behind the radio and happens during aftermarket headunit installations

Mode door is stuck or broken .

I think your problem is the head unit that selects where the air comes out ie. Face, floor, defrost, or hi-level face and floor. If that's not working then it will not let you switch location that you want the air to come out.

Sounds like hose got dislodged. Check under dash & fix. (If you can even get a hand in that area)

Your blend door is probibly not moving all the way to vent position.If you put it on vent there is probibly air blowing on floor or defrost.It may also be opening just a fraction and causing back pressure on the blower motor causing the noise.Is there any difference in outside air or recirculate?

it sounds like the switch lever for the vents, floor and defrost is not switching the vent door that goes to the defroster hose. You need to pull the switch consol out loose from the dash and follow the cable for the defrost that goes to the hose for the defrost. You might also have a broke switch that won't pull the cable enough to open the air for the defrost hose.

cannot switch from defrost to panel airflow 2001 chevy silverado

On some cars the fans will run anytime the heating or cooling system is in the defrost mode try turning it to the vent mode or floor and see if one or both go off