Oily and dusty smell comes out from the AC. - 2010 Toyota Yaris

If it doesn't smell and it's not oily, it's probably condensation from the AC or defogger.

antifreeze anywhere inside the cabin is a sign of a leaking heater core. Rub the liquid between two fingers. If it feels oily, it's coolant.

Feel the water and smell it. If it smells sweet and fells oily, is is coolant. If is isn't oily and has no real smell, it is water. There is a tray under the evaporator and heater cores that catches water/coolant and drains it via a tube thru the firewall to the outside of the car. This tube is probably clogged and needs purged. If you have coolant on the floor, you'll need to replace the heater core. If it is water, purging the hose will solve the problem as the water is just condensation from the AC coils

oil from the hide?

heater core leaking.your heater core is leaking, also check coolant level, your loosing coolant through the heater core

You might have both. The fresh air intake is under the windshield wipers, that vent takes in the fresh air from outside. The filter is usually in the rear seat section on vans and suvs, somewhere, sometimes up front under the dash. You can switch your ac or fresh air control to recirculate and it will cut off the outside air. We always do it on dusty roads and dead skunks. Hope this helps.

When you run your AC, turn if off before you end your trip. You're having it on which builds up mildew. Then when you leave your car there, it stays in the vents. When you turn the car back on, that's the smell you get. Not to mention you should not ever turn your car on with the AC enabled. That's going to cause strain on the initial start of your vehicle that could lead to later complications.

Smell the liquid. If it smells like nothing, it's just water and is only condensation from a very cold exchange unit (like a radiator in reverse). It's just like the water condensing on a cold cup of water. HOWEVER, if it is oily and has an odor, then it is a refrigerant leak and needs to be addressed by a mechanic IMMEDIATELY.

Hope it's the good answer,
matt

coolant isnt oily.
sometimes white vapour (condensation) may visualy appear when first turning on the air conditioner, and that's normal.
oily residue isnt. no idea what it could be.