1. Remove the climate control unit.
2. Inspect for continuity between the fan switch terminals using an ohmmeter.


Climate control unit inspection
Defroster switch inspectionMazda 6 Service Manual: Cruise Control (Some models)
With cruise control, you can set and automatically maintain any speed of more
than about 25 km/h (16 mph).
WARNING
Do not use the cruise control under the following conditions: Using
the cruise control under the following conditions is dangerous and could result
in loss of vehicle control.
...
Mazda 6 Service Manual: AUX/USB mode
Audio can be heard from the vehicle's speakers by connecting a commerciallyavailable
portable audio unit to the auxiliary jack.
A commercially-available, non-impedance (3.5 ) stereo mini plug cable is required.
Contact an Authorized Mazda Dealer for details.
In addition, audio can be played fr ...