smoke coming from the vents?

[Amad18]

Hi , ive got a 04 xterra and just recently my car has smelt like coolant and the defroster hasnt been working. Today i was playing with the a/c and heat controls.. and smoke started coming out of the vents...esspecially when its on hot...it smells like coolant. It has been smoking ever since. Im taking it to the shop tomorrow but i just wanted to know if any of you guys know what it might be. thanks

[hsckris]

Is it like a hazy white kind of a smoke?

If so, every Nissan I have ever owned has done it and I could never figure it out, so I just didn't worry about it (because everything was working fine).

[C-Kwik]

If it smells like coolant, there is a good chance the heater core has a small leak. It would explain the lack of defrosting as it would cause the air to be pretty humid.