Hi, Its not your fault: the filters are too big. I think the frame is about half of an inch short in each direction The a/c installer told me to get 8 x16 inch, thus I have to trim the corners and its still a tight fit. So dont do anything yet. I must get someone to accurately measure the frame, and then I will contact you and talk about what we can to do. Thanks for writing to me.John Buchignani