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: Seat Warmer (Some models)
The front seats are electrically heated. The ignition must be switched ON.
Press the seat warmer switch while the ignition is switched ON to operate the
seat warmer. The indicator lights turn on to indicate that the seat warmer is operating.
The mode changes as follows each time the seat warmer ...
Mazda 6 Service Manual: Variable intake-air system (vis) shutter valve actuator inspection (l3)
1. Remove the air hose. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)
2. Disconnect the vacuum hose from the VIS shutter valve actuator.
3. Connect a vacuum pump to the VIS shutter valve actuator.
4. Apply vacuum and verify that the rod moves.
If the rod dose not move, replace the intake ma ...