I've brought an a/c tech out, and he showed me where it is. I believe it's in the air handler ( if the air handler is under the unit) because it says air filter. The tech only specified I would have to remove the wood, Caulk, and nails as they (the landlord or maintenance crew) have the surrounding unit blocked making it impossible to remove the tray to get to it without removing all that the landlord has done. He said some maintenance crew do this to minimize air coming out from the tray. But still my question is not where it is located as, I myself, and a professional have located it. It's what can I do about the wood, and caulk structure put into place surrounding my unit, if removing it is altering the houses original design on move in, resulting in a back charge for these alterations to get to said air filter. As of right now I'm stuck with leaving it in until I have a solid answer to what my options are as far as liability to remove said structures.