LG Heat Pump Error Code Cx

The Cx code means the electronic expansion valve for the xth indoor unit has an open error. The system detects that a stopped indoor unit has inlet or outlet pipe temperatures below 0°C for 2.5 minutes during cooling, indicating refrigerant is flowing through the unit when it should not be. The "x" in the code corresponds to which indoor unit is affected in a multi-zone setup.

Continuing to operate the system with an active Cx error is not recommended. An open EEV in a stopped indoor unit can cause refrigerant flooding in that unit, which may lead to liquid refrigerant returning to the compressor and causing compressor damage over time. It is best to address the fault before resuming normal operation.

Pressing the reset key (K3) is part of the recommended diagnostic process and will prompt the system to recheck the EEV condition. If the underlying cause was a temporarily loose connection that has since been reseated, the reset may clear the fault. However, if the EEV coil, wiring, or valve body has a genuine fault, the error will return after the system attempts to verify valve operation during cooling mode.

Some basic checks are accessible to a knowledgeable DIYer, such as verifying the EEV coil is fully seated on the valve body and checking that the wiring harness is securely connected to the indoor PCB. Pressing the reset key (K3) after confirming connections can clear the fault if a loose connection was the cause. However, if the EEV coil, valve body, or PCB requires replacement, a licensed HVAC technician with refrigerant handling certification should perform the repair.

Repair costs vary depending on the root cause. If the issue is simply a loose EEV coil or wiring connection, a service call diagnostic fee may be the primary cost, typically in the range of $75 to $150. If the EEV coil requires replacement, parts and labor combined generally range from $150 to $400. A failed valve body or PCB replacement can push total costs higher, often in the $300 to $700 range or more depending on the unit.