2001 Mazda 626 SMOKE COMING FROM VENTS

Are you shure it is smoke and not vapors from the anti freeze? Dose it cover the windshielsd inside and is hard to come off. If this is the case I would say that either the drain hole could be clooged or that there is a leak in the heater core. You will definatly tell if it is a anti freeze leak, it feels slimy and is hard to get off the windows.

Depending where you live and the weather. You could by pass the heater core if you live in a warm climate and don't need the heater that much. You would have to tun the two hoses together bypassing the heater core. A new heater core could cost up to around 250. And labor could cost around 400. Rates change with each garage so check around if you are thinking about fixing it. You could always try some stopleak, not saying that it would take care of the problem. Good luck with what you decide. If you have a friend that is a mechanic he might do it for less.