1. Measure the temperature around the cabin temperature sensor.
2. Measure the resistance between terminals of the cabin temperature sensor.

Cabin temperature sensor removal/installation
Evaporator temperature sensor removal/installationMazda 6 Service Manual: Tire house trim removal/installation
4SD
1. Remove the rear scuff plate.
2. Remove the rear seat side.
3. Remove the fastener.
4. Pull the tire house trim upward, then disengage clips A from the body, and
remove the tire house trim.
5. Install in the reverse order of removal.
5HB
1. Remove the rear scuff plate.
2. Pull the ...
Mazda 6 Service Manual: Scheduled Maintenance (U.S.A., Canada, and Puerto Rico)
Follow Schedule 1 if the vehicle is operated mainly where none of the following
conditions (severe driving conditions) apply.
Repeated short-distance driving
Driving in dusty conditions
Driving with extended use of brakes
Driving in areas where salt or other corrosive materials are used
...