Why is steam coming out of my vents ? The air conditioner/heater is off and, all of a sudden, hot vapor starts coming off the dashboard vents, and keeps flowing even when I turn the car off.
It's pretty scary.
Please help !!

 

Is there an odor or color to the mist?

When the car is off, does the 'flow' slow down or does it stop suddenly?

If you move the **** to the floor vents, does it come out from the floor or only from the dash vents?

 

Heater core sounds like it's going. When you replace it I recommend the Behr not the Nissens, a brand new Nissens exploded in my car and made a mess.

 

+1 on the core.

 

Yes there is a strong humid odor, the color is whitish, like water vapor. It slows down when I turn off the car and then stops. Havent checked moving the *****.

 

Thanks Bobeck. Theres something else: I have started adding water to my plastic reservoir by the radiator cause it goes somewhere.Is it related ?

 

That mist you're getting? It's what you're adding to the radiator reservoir!