I have a order that smells like oil or burnrd leaves. I've gotter several different suggestions but no solution. I recently changed the cabin air filter but the order returns. odor is not everyday but almost on and off.
Strong Odor From time to Time Under Dash on 2006 Ford Taurus
Try turning on your heater full blast and then spraying a mold killer like Lysol in to the intake vents in your cowl area where your windshield wipers are. Moisture builds up inside your heater/AC plenum and then gets moldy which smells. Make sure that your A/C vent tube is not plugged and can drain properly. It is under your car. When you spray in the mold killer, some should drip out which will help you find it. Also clean off your cowl area of all debris, especially the leaves and such. That is how the mold enters your system. Your blower motor sucks in the mold spores off the old dead leaves.