I have had an ongoing problem with 'fog' coming out of the vents in my 98 Dakota.This happens even if all ventilation controls are in OFF. It doesn't pour out - just sort of floats out.Also fogging up windshield when in defrost.Took it to shop - they pressure tested heater core - no leaks. They evacuated and re-charged the A/C to assure proper coolant level . Now, at least the defrost is able to clear the windshield - but the fog continues out of the vents even when system is off. I'm thinking this is still some sort of A/C problem. Anyone have any experience with this sort of problem?

Thanks

 

I'm having a similar problem with my 2004. Seems to me like it happens when it is humid conditions outside, like after a rainfall. If i have the fan on high it disappears but if it's on the two low settings a patch of condensation builds up on the windshield.

I thought it was due to the humid/cold air coming out of the vent, cooling that portion of the windshield and causing it to form condensation.