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: Generator removal/installation
Warning
When the battery cables are connected, touching the vehicle body with
generator terminal B will generate sparks. This can cause personal injury, fire,
and damage to the electrical components. Always disconnect the battery negative
cables before performing the following operation.
...
Mazda 6 Service Manual: Washer fluid-level sensor inspection
1. Disconnect the negative battery cable.
2. Remove the washer tank. (See WASHER TANK REMOVAL/INSTALLATION)
3. Insoect for continuity between the washer fluid-level sensor terminals
using an ohmmeter.
4. Verify that the windshield washer motor operates.
If not as specified, replace the ...