LG HVAC Error Code 47

Error code 47 on an LG HVAC system means the outdoor unit PCB has detected that the single-speed compressor discharge pipe thermistor signal is out of range, indicating either an open or shorted sensor circuit. The discharge pipe thermistor monitors refrigerant temperature at the compressor outlet. The system shuts down this protection to prevent compressor damage from undetected overheating conditions.

You should not continue operating the system while error code 47 is active. The discharge pipe thermistor is a compressor protection sensor, and without a valid reading from it, the system cannot properly detect compressor overheating. Running the unit with this fault present risks serious and costly compressor damage.

A power reset may temporarily clear the error and allow the system to restart, but code 47 will return if the underlying fault with the thermistor, wiring, or connector has not been fixed. Repeatedly resetting the unit without addressing the cause risks compressor damage. The fault should be properly diagnosed and repaired before relying on the system for continued operation.

Diagnosing error 47 requires a multimeter and knowledge of how to safely access the outdoor unit. A knowledgeable DIYer can test the thermistor resistance by placing it in water at a known temperature and comparing to the spec values of 244,000 ohms at 20 degrees C and 24,400 ohms at 90 degrees C. However, if the PCB needs replacement or refrigerant components are involved, a licensed HVAC technician should perform the work.

Repair costs vary depending on the root cause. Thermistor replacement is generally the least expensive fix, typically ranging from around $50 to $200 including labor. A connector repair or wiring harness fix may fall in a similar range. If the outdoor unit PCB has failed, costs can range from several hundred to over a thousand dollars depending on the unit model and labor rates in your area.