Have the cabin air filter changed.
There may be something blocking the deflectors from sending air up there.
change the cabin filters
Depends on the smell. What does it smell like?
Perhaps a dead mouse.
heater core
you need a new heater core
Most of the time it is caused by a hole in the heater core, do you smell a sweet smell? The sweet smell would be the antifreeze.
Your house may smell like electrical fire or nail polish remover is coming out of the AC vents because you have fried wiring. You should make sure that you do not have a wall fire.
bad heater core bad heater core
sounds like your air conditioner compressor is bad.
Generally, with that smell- the heater core has gone bad.
someone wetting themselves in the car because they couldn't get to a toilet quick enough