When I started the car without the filter and cover, the AC sputtered and then seemed to perform badly that day. I have since put the cover back on and the AC now is working properly.

Still a mystery as to how that odor settled in my filter.

There were leaves and debris in the on the filter. How do they get there? From the cowl?

I am one of those rare individuals that drives usually with my windows down (except on the interstate or when it is hot) so I guess that I my interior and lungs are accumulating fine dust