2004 Acura MDX Cabin air filter

Yes, it is behind the glove box. Not too difficult to replace, but you may have to cut a plastic brace to gain access (as per the factory manual).
There is also a dome shaped screen in the center console that is the "filter" for the rear A/C. It's accessible by removing the driver's side center console trim. It clogs up with dust and carpet lint and will restrict the volume for the rear blower.