Samsung Heat Pump Error Code E425

E425 indicates that the Samsung heat pump has detected either a reversed phase sequence or a missing phase in the incoming 3-phase power supply. The unit monitors all three power legs to ensure correct voltage and rotational order before allowing the compressor and motors to operate. This error prevents the system from running until the electrical supply issue is resolved. It is an electrical safety protection feature, not a component malfunction in most cases.

A simple power reset will not clear E425 if the underlying phase problem still exists. The unit will re-detect the fault immediately upon restart and return the error. The root cause, whether a missing phase, reversed wiring, or a tripped breaker, must be corrected first. Once the 3-phase supply is confirmed correct and balanced at approximately 380V per leg pair, the error should clear on the next startup.

Repair costs depend heavily on the root cause. If the issue is a tripped breaker or a wiring correction at the disconnect, costs may range from minimal service call fees up to a few hundred dollars. If a phase detection board inside the unit has failed, parts and labor costs could range from a few hundred to over a thousand dollars. Utility-side phase loss may require the power company to intervene at no cost to the homeowner.

Diagnosing E425 requires measuring 380V 3-phase voltages at internal connector CN82, which involves exposure to potentially lethal voltages inside the unit. Qualified HVAC technicians or licensed electricians should perform this work. If the issue is a tripped breaker at the panel, a homeowner can safely reset it, but any wiring investigation inside the unit or at the disconnect requires a professional.

No. The unit is designed to shut down and display E425 specifically to prevent operation under dangerous electrical conditions. Running a compressor on a missing or reversed phase can cause immediate and severe mechanical damage to the compressor and motor windings. The system should remain off until the phase issue is fully resolved by a qualified technician.