why is dirt coming out of my vents in my truck?

[dropdead17]

i have a 97 dodge ram 1500. it doesn't smell or anything it looks like dirt comes out my vents the smoke is brown ill be driving to school and ill have to roll my windows down because it just starts coming out of my vents idk what it is. it doesn't have a smell it just looks like dirt dust or something idk. why is this happening?

 

[HoWdY]

Do you drive on a dirt road?

 

[SID]

they started using vent filters in 1998 yours doesn't have any . start by blowing compressed air in your system. if you do have a filter they are under the clove compartment. but im pretty sure they invented that in 1998