Exact same situation. I used to date a girl who frequently smoked in my car. When we broke up, I had hoped the musty smell would leave with her, but it has not. I don't know what this is.
We bought this vehicle brand new. We don't smoke or allow anyone else to smoke. We now have a musty smell coming through vents when putting on defogger and air condition.
I have the same smell but i only smell it when my AC is on and running on low, when it is on high it is perfectly fine but once you get past the 2nd notch going back toward off it has a really funky smell.
i noticed that funky smell as soon as i bought it ,turned on the ac and ick, i thought the previous owner must have been some weird freak , the car was super clean so it didn't make sense though
When returning to van and starting ac we get a musty odor.
smells musty/moldy when turning on air or heat
when the air is running in the morning it smell's like sewer.
Foul odor coming from ac/heat vents
weard smell coming from the vent while a/c is on or heat