LG Air Conditioner Error Code CH65

CH65 indicates an open or short circuit in the heatsink thermistor, which is the temperature sensor mounted on the inverter module's heatsink. The control board monitors this sensor to protect the compressor drive electronics from overheating. When the sensor signal falls outside the valid resistance range, the unit shuts down and displays CH65. The fault points to either a failed sensor, damaged wiring, or a loose connector.

No. The CH65 fault causes the unit to shut down precisely because the control board can no longer monitor heatsink temperature. Attempting to bypass or ignore this fault could allow the inverter electronics to overheat without protection, potentially causing permanent damage to the inverter module or creating a fire hazard. Leave the unit off until the fault is diagnosed and repaired.

Repair costs vary depending on which component has failed. A thermistor replacement is generally an inexpensive part, with total repair costs typically ranging from around $80 to $200 including labor. If the control board requires replacement, costs can range from $250 to $600 or more depending on the model and local labor rates. Getting a diagnostic visit from a certified technician will give you a precise estimate for your specific unit.

A knowledgeable DIYer can check for a disconnected thermistor connector and reseat it, which requires no parts and may resolve the fault if the connection was simply loose. Testing the thermistor's resistance with a multimeter is also within reach for someone comfortable with basic electrical diagnostics. However, replacing the thermistor or the control board involves working near high-voltage inverter components, and that work is best handled by a qualified technician.

A power reset may temporarily clear the fault code and allow the unit to restart, but CH65 will return if the underlying problem with the thermistor or its wiring has not been corrected. Repeated resets without repairing the root cause can put the inverter components at risk. A reset is only appropriate as part of a diagnostic process after a repair has been made.