Smoke from vents

i have recently notice smoke coming from the defroster vents and the air conditioning vents in my 1990 tracker. i was just wondering where this could be coming from and what it could mean. i want to catch any problem before it gets big.

possible heater core? does it have any odor to it? have you checked your coolant level lately?

ill try checking my coolant level, my car seems to go through it fast.