Diagnostic codes covered
EC 55
Description: If the sampling voltage is 0V or 5V, the LED displays the failure code. Recommended parts to prepare: IPM module PCB Connection wires Sensors Outdoor main PCB
Troubleshooting workflow

Related diagnostic checks
Workflow source: original 37MGRA-02SM service-manual PDF. Error-code names cross-checked against 37MGRA-04SI.
