2000 Miata

2000 Miata - How difficult is it to replace the A/C filter in the cabin? Do I need to disassemble the dash?

It would appear your Miata doesn’t have a cabin air filter. Here’s a TSB from Mazda about removing odors from the ventilation systems of various Mazda models. And those vehicles that do have a cabin air filter show how it’s changed. However. they don’t indicate that your Miata has a cabin air filter.
http://www.miatamania.com/graphics/products/miata_service_bulletins/07-006-08-2016.pdf
Tester

I couldn’t find a replacement listed for it on rockauto. Why do you think it has one?