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

Water temperature sensor removal/installation
Refrigerant pressure switch removal/installationMazda 6 Service Manual: Interior Care
WARNING
Do not spray water into the vehicle cabin: Spraying water into the
vehicle cabin is dangerous as electrical devices such as the audio and switches
could get wet resulting in a malfunction or vehicle fire.
NOTE
Do not wipe the interior using alcohol, chlorine bleach, or organic solv ...
Mazda 6 Service Manual: Windshield Defrosting and Defogging
Press the windshield defroster switch. In this position, the outside air position
is automatically selected, and the air conditioner automatically turns on. The air
conditioner will directly dehumidify the air to the front windshield and side windows.
Airflow amount will be increased.
WARNING
...