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: Refrigerant lines removal/installation
1. Remove the battery.
2. Discharge the refrigerant from the system. (See RECOVERY.) (See CHARGING.)
3. Remove the washer tank. (L.H.D. only) (See WASHER TANK
REMOVAL/INSTALLATION.)
4. Remove the air cleaner cover, air cleaner element and air cleaner case.
(See INTAKE-AIR SYSTEM
REMOVAL/INST ...
Mazda 6 Service Manual: Expansion valve removal/installation
1. Disconnect the negative battery cable.
2. Discharge the refrigerant from the system. (See RECOVERY.) (See CHARGING.)
Caution
If moisture or foreign material enters the refrigeration cycle,
cooling ability will be lowered and abnormal noise will occur. Always
immediately plug open fitt ...