1. Verify that there is no continuity between antenna feeder terminals A and B using an ohmmeter.

2. Inspect for continuity between the antenna feeder terminals using an ohmmeter.

Front antenna feeder inspectionMazda 6 Service Manual: Owner Maintenance Precautions
The owner or a qualified service technician should make these vehicle inspections
at the indicated intervals to ensure safe and dependable operation.
Bring any problem to the attention of an Authorized Mazda Dealer or qualified
service technician as soon as possible.
At Least Twice a Year (For ...
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 ...