Samsung Air Conditioner Error Code P520

P520 indicates that the outdoor unit's Electronic Expansion Valve (EEV) has failed its open position self-diagnosis test, which is designated as open fault 2. The system runs an automatic check on the EEV's ability to move to the fully open position and triggers this code when the valve does not respond correctly. This is a refrigerant flow control issue located in the outdoor unit and requires professional diagnosis.

Running the system while P520 is active is not recommended. A faulty EEV can cause the system to operate with improper refrigerant flow, which may lead to compressor overheating, liquid slugging, or further damage to refrigerant circuit components. Shut the unit down and schedule a service call to prevent additional damage.

Repair costs vary depending on which component has failed. EEV replacement parts and labor can range from around $200 to $600 or more depending on the unit model and local labor rates. If the outdoor PCB also requires replacement, costs can increase further. A diagnostic visit fee is typically charged separately before repair costs are confirmed.

Most of the repair steps for P520 involve working with refrigerant circuit components, high-voltage wiring inside the outdoor unit, and precision electronic parts. While a homeowner can check for obviously loose or damaged wiring at the outdoor unit harness, replacing the EEV or the outdoor PCB requires refrigerant handling certification and technical tools. It is strongly recommended to have a certified HVAC technician perform the repair.

A power reset may temporarily clear the code, but P520 will return if the underlying issue with the EEV, its wiring, or the outdoor PCB has not been resolved. The self-diagnosis routine runs automatically and will re-trigger the fault during normal operation. A reset alone is not a fix and should not be relied upon as a solution.