1. Remove the air filter.
2. Inspect the air filter.
Note

Air filter removal/installation
A/c unit removal/installationMazda 6 Service Manual: Rear drain hose removal
1. Remove the headliner.
2. Remove the trunk side trim. (4SD)
3. Remove the trunk side upper trim and trunk side trim. (5HB)
4. Disconnect the rear drain hose from the sunroof frame.
5. Remove the rear drain hose from the clips.
6. Pull the rear drain hose into the room side.
7. Remove the rea ...
Mazda 6 Service Manual: Heater core inspection
1. Remove the A/C unit. (See A/C UNIT REMOVAL/INSTALLATION.)
2. Remove the heater core from the A/C unit.
3. Inspect for cracks, damage, and coolant leakage.
If any problems are found, replace the heater core.
4. Inspect for bent fins.
If any are bent, use a flathead screwdriver to stra ...