Diagnostic procedure
Mazda 6 Service Manual: Heater core inspection
1. Remove the A/C unit. (See A/C UNIT REMOVAL/INSTALLATION.)
2. Remove the heater core from the A/C unit.
3. Inspect for cracks, damage, and coolant leakage.
If any problems are found, replace the heater core.
4. Inspect for bent fins.
If any are bent, use a flathead screwdriver to stra ...
Mazda 6 Service Manual: Engine control system operation inspection
Main Relay Operation Inspection
Verify that the main relay clicks when the ignition switch is turned to ON
position and off.
If there is no operation sound, inspect the following.
- Main relay (See RELAY INSPECTION.)
- Harness and connector between ignition switch and main relay termi ...