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: Trunk Lid
WARNING
Never allow a person to ride in the trunk: Allowing a person to ride
in the trunk is dangerous. The person in the trunk could be seriously injured or
killed during sudden braking or a collision.
Do not drive with the trunk lid open: Exhaust gas in the cabin of a vehicle
is dangerous. ...
Mazda 6 Service Manual: Driving on Uneven Road
Your vehicle's suspension and underbody can be damaged if driven on rough/uneven
roads or over speed bumps at excessive speeds. Use care and reduce speed when traveling
on rough/uneven roads or over speed bumps.
Use care not to damage the vehicle's underbody, bumpers or muffler(s) when driving ...