1996 Nissan Maxima middle vents won't blow air

Middle vents not blowing air but driver and passenger vents are low med and high even when sidevents closed it still trying to force it’s self through the middle there’s no cabin air filter and also the passengers side on recirculate has and exhausted smell also when not on recir. It blows at different speeds when it’s set to face on 4 aslo seems like it’s switching on it’s own to recir.air when the button is not on help!

Likely electric actuators under the dash that open and close the doors have failed. It could be one, it could be 2. If everything else on this car still works OK, take it into a good independent mechanic and have them take a look. Shouldn’t be too expensive.