what color is the smoke. What does it smell like?
Lack of oil or water??
Under the hood in front of the transmission dip stick is a vacuum line. If it is disconnected or split it will make the air vents not work. If that's not it check your fuses.
Assuming that the blower motor isn't on fire, it's probably the heater core. Does the smmoke smell sweet. If yes that's antifreeze. The smoke does smell like anti-freeze. Does this suggest that the heater core is the problem?
You need to replace the heater coil !
A fuse usually blows when there is a short. It's possible you have a short in the wiring someplace.
Low of transmission fluid or a bad torque converter.
The vacuum supply line from the engine is disconnected or broken. When the vacuum supply is cut off the system defaults to the defrost mode.
There is a conduit with a fastener at the end. When I obtained my 2005 Buick LeSabre my rear air vents seemed to blow less than I had expected. After further inspection, I discovered that the conduit was not attached to the vent stack. So I played with it until I got it to slide into the vent stack and it seems to work as I would have expected at present.
Probably a bad head gasket or a cracked head or both.
# Why doe the gas furnace blow black smoke?
Defective blower motor?
The pseudolink at the bottom will guide you to videos for this. youtube.com/results?search_query=how+to+blow+smoke+rings