Error Code: EC 72 – Lack Phase Failure of Outdoor DC Fan Motor

Error Code: EC 72 – Lack Phase Failure of Outdoor DC Fan Motor

What this means:
The system has detected an imbalance or missing signal in one of the three electrical phases powering the outdoor DC fan motor. This typically means that one phase is not delivering current properly, which can result from a motor failure, damaged wiring, or PCB malfunction.

Try this first (quick reset):

1. Turn off power to the unit completely.

2. Wait 2 full minutes.

3. Turn the system back on and check if the error disappears.

• If the error clears — it may have been a temporary fault.

• If the error persists — continue with the steps below.

Next steps (for technicians):

1. Check for open circuits in the 3-phase fan output:

   • Look for broken wires or loose terminals leading from the PCB to the fan motor.

2. Inspect wiring connections:

   • Ensure all terminals on the fan motor are secure and properly connected.

   • Correct any miswiring.

3. Measure 3-phase resistance of the fan motor (UVW):

   • Resistance between U–V, V–W, and U–W should be symmetrical (nearly equal).

   • If values differ or one phase reads near 0 ohms, the fan motor is faulty and should be replaced.

4. If wiring and fan motor are good:

   • Replace the outdoor main PCB.

What you might need:

• DC fan motor

• Outdoor PCB

• Connection wires

Helpful tip:
This error is triggered when the current in one or more fan motor phases is consistently near zero. Always test resistance before replacing the PCB, and confirm that no wires are loose at the motor terminals.

Click here to view the detailed guide.TS38