some of the stuff you can get to easy. the quickest way into most systems is through the blower opening. if you can open up the system that way you may be able to use a small mirror to see whats jamming your system. I have found everything from pills to pencils stuffed in the duct work. my old dodge has mice living in the ducts and I just open the duct up and shove in the shop vac to clean them out.