LG Air Conditioner Error Code E703

E703 indicates the system has detected the indoor unit's Electronic Expansion Valve (EEV) in an unexpectedly open position during its first detection event. The EEV controls refrigerant flow into the indoor coil, and this fault means the control system has lost proper control of that valve. The error is typically caused by a wiring problem, a corroded coil connection, or a failed EEV coil.

Pressing reset key K3 is part of the recommended diagnostic procedure and may temporarily clear the fault. If the error returns after reset, the underlying cause, such as a faulty coil, corroded connection, or wiring fault, has not been resolved and must be addressed. A recurring E703 after reset indicates a component repair or replacement is needed.

Repair costs depend on the root cause identified during diagnosis. If only a wire connection needs to be reseated or cleaned, costs may be limited to a service call fee, typically in the range of $75 to $150. If the EEV coil requires replacement, parts and labor combined can range from $150 to $400 or more depending on the model and local labor rates. A full EEV valve assembly replacement will generally fall at the higher end of that range.

Some basic checks, such as inspecting the EEV wire harness for loose connections and pressing the reset key K3 to clear the fault, can be done by a knowledgeable homeowner. However, measuring coil resistance, inspecting for rust on terminals, and replacing the EEV coil or valve assembly require familiarity with electrical testing and refrigerant components. It is recommended to have a qualified technician perform the full diagnosis if the reset does not clear the fault.

Operating the unit continuously while the E703 fault is active is not recommended. An uncontrolled open EEV can lead to improper refrigerant flow, reduced efficiency, and potential stress on the compressor. The system should be inspected and the fault resolved before returning the unit to normal operation.