We have a Payne/Carrier heating system, Model PG8JAA/MAA. Where, exactly, is the filter(S)?? How to change? --Desperate For Clean Air and Filled With Gratitude For Help in Philly

There is no exact spot. The filters are installed in a area of the installers choice which is somewhere on the return air side of the unit. The factory ships your style/brand unit with hog hair filters usually and those are usually located in the blower compartment of the unit. Hog Hair filters are worthless so if that is what you find I would replace them with something better.