I have dust coming in my defrost and passenger vents when I go above 30 mph. It doesn't matter whether I have my A/C on or off. When I run my heat or defrost it doesn't usually happen. Just when I was using my A/C. Any ideas what I have going on? I have changed the in-cabin air filter and it doesn't help. Thanks,

 

Is it actual dust or possibly a mist from a small refrigerant leak in the evaporator in the dash?

 

It is actual dust you can see it coming in and smell it.