LG Heat Pump Error Code P755

P755 indicates that the outdoor unit Electronic Expansion Valve (EEV) failed a close self-diagnostic test. The system commands the valve to fully close and then checks whether that command was successfully completed. When the diagnostic detects a failure on the second closing test, it stores P755 and interrupts normal operation to protect the refrigerant circuit.

A power reset may temporarily clear the fault code if the EEV was in a momentary binding condition, but the code will return if the underlying cause is not corrected. Persistent P755 errors after a reset confirm that there is a real mechanical or electrical fault with the EEV, wiring harness, or outdoor PCB that requires hands-on diagnosis.

Repair costs vary depending on the root cause. EEV coil or valve replacement typically falls in the range of $200 to $600 including parts and labor, while an outdoor control board replacement can range from $400 to $900 or more depending on the model. If refrigerant system contamination is involved, additional costs for flushing and recharging the system will apply.

Most repairs for P755 require a licensed HVAC technician. Inspecting and replacing the EEV involves working with the refrigerant circuit and the outdoor unit control board, both of which require proper tools and certifications. A knowledgeable DIYer can check the EEV wiring harness for visible damage or loose connectors, but component-level diagnosis and refrigerant handling must be done by a qualified professional.

It is not recommended to continue running the heat pump while P755 is active. A malfunctioning EEV that cannot close properly disrupts refrigerant flow control, which can lead to compressor damage or other refrigerant circuit faults. The system may shut itself down automatically as a protective measure, and continuing to attempt operation before repair can worsen the damage.