E4 72 (FJM Outdoor) — Inverter micom zero-crossing error

What does E4 72 mean?

The FJM outdoor unit displays E4 72, indicating that the inverter's microcomputer (micom) has detected an issue with the zero-crossing signal. This signal is crucial for the proper synchronization and operation of the inverter.

• Inverter board malfunction
• Electrical noise or instability in the power supply
• Faulty components associated with zero-crossing detection

Click steps to track your progress.

1. 1

   Turn off the main power to the FJM outdoor unit at the circuit breaker for at least 10 minutes.

2. 2

   Restore power and attempt to restart the system.

3. 3

   Ensure the outdoor unit has a stable and clean power supply, free from significant voltage fluctuations.

4. 4

   If the error persists, contact a qualified technician to inspect the inverter PCB for component faults.