Figured I'd change my cabin air filter as the car has 38000 miles and is two+ years old. The shop manual tells you to remove the glove box. There's a little string attached to the right side of the glove box. Its attachment can be slipped through the keyhole-shaped slot to disconnect it. Flex in the sides, then the box can swing down and you can lift it off its hinges. No problem so far.
With a flashlight, you can see the cabin air filter door because it says "cabin air filter door" right on it. I felt around for some means of releasing the door without any success. The shop manual says "remove the door". As is so typical of shop manuals, it make no mention of how you are supposed to do that. Absent any further clue, I pried gently on the plastic door with a plastic trim tool which, in short order produced a snapping sound accompanied by flying plastic. Prying on the other end produced the same results but got the door off.
The old filter (very dirty) came out easily at that point. Installing the new filter (about $9.50 at Autozone) requires that you bend down the right side flap to get by the "damper" mechanism. They must have anticipated the destructive disassembly because they provided screw holes to hold the door back in place at the upper left and lower right corners. A couple of #8 self-tapping or sheet metal screws about 3/4" long did the trick.
Snap the string back into the glove box, hook on the hinges and the job is done.
Too late for me but if anyone knows the trick for removing the door without breaking off the tabs this would be a good time to post it up here.

 

just go through it http://www.aceprohvac.com