Samsung Heat Pump Error Code E477

E477 indicates that the sump temperature sensor for fixed compressor 1 has broken away from its mounted position on the compressor shell. This sensor monitors the oil sump temperature to protect the compressor during operation. When the sensor loses contact with the compressor body, the control board triggers this fault to prevent unmonitored compressor operation. The fix typically involves locating the sensor, repositioning it, and securing it properly.

It is not advisable to continue operating the heat pump with E477 active. The sump temperature sensor protects the compressor from conditions like refrigerant flooding and lubrication overheating. Running the compressor without reliable sump temperature monitoring risks undetected damage to the compressor, which is one of the most expensive components in the system. The unit should remain off until the sensor is properly reattached and the fault is cleared.

If the sensor only needs to be repositioned and reattached with existing or inexpensive hardware, the primary cost is the service call, typically in the range of $75 to $150 depending on your location and service provider. If the sensor itself is damaged and requires replacement, parts and labor combined could range from $150 to $400 or more. Getting a diagnostic visit to confirm the extent of the issue before committing to parts is a good approach.

If you are comfortable working around refrigerant equipment and can safely access the compressor compartment, visually confirming and reattaching the sensor is a straightforward physical task. However, working inside a heat pump involves high-voltage components and potentially pressurized refrigerant lines, so technician service is strongly recommended if you are not experienced with HVAC systems. If mounting hardware is broken or the sensor itself needs replacement, a qualified technician should handle the repair.

Simply resetting the unit will not permanently clear E477 if the sensor is still detached or improperly positioned. The fault will return as soon as the control board checks the sensor again and detects the same problem. The sensor must be physically reattached and secured to the compressor shell before the reset will hold and normal operation can resume.