Air Filter Removal/Installation
1. Disconnect the negative battery cable..
2. Remove the side wall..
3. Disconnect the evaporator temperature sensor connector.
4. Disconnect the power MOS FET connector. (Full-auto air conditioner)
5. Disconnect the resistor connector. (Manual air conditioner)
6. Remove in the order indicated in the table.

Screw
Air filter cover
Air filter (2)
(See Air Filter Installation Note.)
Air filter (1)
(See Air Filter Installation Note.)
7. Install in the reverse order of removal.
Air Filter Installation Note1. Insert the air filter projection between the ribs of the A/C unit and assemble the air filter (1) in the order shown in the figure.

2. Assemble the air filter (2) in the order shown in the figure.

Test yourself
A quick Mazda 3 quiz: every answer comes with an explanation and a link to the manual page.