When I purchased my 05 Bonn, the cabin filter was missing.. at first I bought one at Wallmart, a Fram and it had no frame cage to hold it in the car. the other one i bought off EBAY had a cage alredy on the filter, it was jsut a plug in and done filter. and without that filter you can get a buncha junk in the squirrel cage. mine was off balance until i got a filter for it, ( well mainly because I cleaned out the crap when i bought the filter )