LG Air Conditioner Error Code 55

Error code 55 on an LG air conditioner means the outdoor unit's main PCB has not received a communication signal from the central controller for 3 consecutive minutes. This is a transmission timeout fault that prevents normal system operation. The cause can be a configuration issue, wiring fault, or a failed control board on either end of the communication link.

Error code 55 typically prevents normal operation, as the outdoor unit cannot receive commands from the central controller. The system should not be forced to run while this fault is active. Attempting to bypass the error without resolving the root cause could lead to further damage to the control boards.

If the fault is only a configuration error, the repair cost is typically limited to a service call fee, generally in the range of $75 to $150. If the central controller PCB or outdoor unit main PCB requires replacement, parts and labor can range from $300 to $900 or more depending on the specific model and local labor rates. A technician will need to diagnose the exact cause before providing an accurate estimate.

If the error is caused by an incorrect group setting, a knowledgeable user or installer can resolve it by reviewing and correcting the group address configuration in the central controller. However, if the fault involves damaged wiring or a failed PCB, a qualified HVAC technician should perform the repair. Working inside commercial or multi-zone systems involves high-voltage components and complex control wiring.

A power reset may temporarily clear the error display, but if the underlying communication issue is not resolved, the fault will return within 3 minutes once the system restarts and the outdoor unit again fails to receive a signal. The group settings and hardware must be inspected and corrected to achieve a lasting fix.