steam comes out of the vents when the air conditioner is used when conditions are humid. Steam is so bad that you cant see out the windows.
May be a leaking heater core. Check your coolant with cold engine and don’t drive with low coolant
Does it smell like coolant? Then tcmichnorth is on the right track.
If not, your AC might be low on refrigerant which sounds counterintuitive but can happen.
Fog. When the conditions are just right the humid air will come out as a fog.
Take it out of recirculate.