Error Code: EC 55 – Outdoor IPM Module Temperature Sensor Malfunction

Error Code: EC 55 – Outdoor IPM Module Temperature Sensor Malfunction

What this means:
This error occurs when the IPM (Intelligent Power Module) temperature sensor is either missing, misconnected, or returning a fixed voltage of 0V or 5V, which indicates a fault. The system will shut down to prevent damage to the inverter.

Try this first (quick reset):

1. Turn off power to the unit completely.

2. Wait 2 full minutes.

3. Turn the unit back on and check if the error clears.

• If the error clears — the system is operating normally.

• If it returns — continue below.

Next steps (for technicians):

If the radiator does not have a sensor:

1. Inspect fastening screws between the PCB and the IPM radiator.

   • If loose → tighten the screws and apply silicon thermal grease.

   • If secure but the error persists → replace the IPM module PCB.

If the radiator has a sensor (TH):

1. Check wiring between the sensor and PCB:

   • If miswired or loose → ensure proper connection.

2. Measure the sensor’s resistance:

   • If out of range → replace the sensor.

   • If within range but the fault remains → replace the outdoor main PCB.

What you might need:

• IPM module PCB

• Temperature sensor (TH)

• Outdoor main PCB

• Connection wires

• Silicon thermal grease

Helpful tip:
This error typically occurs during startup self-check. A fixed voltage of 0V or 5V from the sensor pin is a clear indicator of disconnection or internal failure.

Click here to view the detailed guide.TS42