LG Air Conditioner Error Code 221

Error code 221 indicates a liquid pipe temperature sensor fault on HR unit 6. The control board has detected either an open circuit or a short circuit in the sensor or its wiring, meaning the sensor is not returning a valid resistance reading. The system stops normal operation and displays this code to prevent damage from unmonitored refrigerant temperatures.

A power reset may temporarily clear the error display, but if the underlying sensor fault still exists, the code will return once the system attempts to operate and reads the faulty signal again. The root cause, whether a bad connection, damaged cable, or failed sensor, must be corrected before the error will stay cleared.

If only a connector needs to be reseated or cleaned, there may be little to no parts cost, with the expense being primarily a service call fee, typically in the range of $75 to $150. If the sensor or wiring harness requires replacement, parts costs can range from $20 to $100 or more depending on the specific component, with total repair costs including labor commonly falling between $150 and $350.

Basic checks such as inspecting the sensor connector for loose connections and looking for visible cable damage are tasks a knowledgeable DIYer can perform. However, accessing the HR unit internals, measuring thermistor resistance accurately, and replacing sensor components in a multi-zone heat recovery system typically requires a trained HVAC technician. Working on refrigerant systems also requires proper certification in most regions.

It is not recommended to continue running the system while this error is active. The liquid pipe temperature sensor provides data the system uses to protect compressors and manage refrigerant flow. Operating without a valid sensor reading can lead to inefficient performance or component damage. The unit may also refuse to run at all until the fault is resolved.