LG Heat Pump Error Code CH65

CH65 indicates a fault in the heatsink temperature sensor circuit. The error activates when the sensor signal implies a temperature at or above 130°C (short circuit condition) or below -30°C (open circuit condition). The heatsink sensor protects the inverter electronics, so the unit will typically shut down when this code appears. Diagnosis starts by checking the sensor connector and measuring resistance (5k ohm at 25°C) or voltage (2.5Vdc at 25°C).

It is not advisable to continue operating the unit while CH65 is active. The heatsink sensor protects the inverter and compressor drive electronics from thermal damage. If the sensor circuit is open or shorted, the control board cannot reliably monitor heatsink temperature, which could allow the inverter components to overheat without triggering a proper shutdown. Keep the unit off until the fault is diagnosed and repaired.

Repair costs vary depending on the root cause. Replacing the heatsink NTC thermistor is generally the least expensive fix, with parts typically in the range of $15 to $60 and labor adding $75 to $150 depending on your region. If the fault involves a damaged wiring harness or a failed inverter control board, total repair costs can rise to $200 to $600 or more. Getting a diagnostic visit from a certified technician will clarify the exact cause before committing to parts.

A knowledgeable DIYer comfortable with a multimeter can perform the initial diagnostic steps: inspecting the sensor connector and measuring resistance across the unplugged thermistor. If the connector is simply loose, reseating it may resolve the fault. However, replacing the thermistor, tracing wiring faults, or diagnosing a failing inverter board typically requires familiarity with heat pump electrical systems, so professional service is recommended if basic checks do not resolve the issue.

A power reset may temporarily clear the CH65 code, but the fault will return if the underlying problem with the sensor circuit has not been corrected. If the error reappears immediately or shortly after a reset, the thermistor, its wiring, or the connector requires attention. Resetting without repairing is not a long-term solution and risks further damage to inverter components.