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Error code reference

LG Air Conditioner Error Code 65

Heat sink thermistor error (open/short)

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What the 65 error code actually means

Your LG air conditioner has detected a problem with a small temperature sensor inside the outdoor unit that monitors the inverter's heat level. The sensor is either not sending a signal at all or is sending a signal that indicates a short circuit, so the system has shut down to prevent damage. A technician will need to inspect the sensor wiring and the sensor itself to determine whether it needs to be replaced.

Diagnostic procedure

The full 65 procedure

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1
First diagnostic step
Check connector connection, check sensor resistance (5KΩ at 25°C unplugged) or voltage (2.5Vdc at 25°C plugged).
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Most common causes of 65

Ranked by how often they cause this code
  1. 1Loose or corroded sensor connector
  2. 2Failed NTC thermistor sensor
  3. 3Damaged wiring harness
  4. 4Moisture or contamination inside the outdoor unit
  5. 5Faulty outdoor unit control board

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Questions people ask about 65

What does 65 mean on a LG air conditioner?
Error code 65 on an LG air conditioner indicates a fault with the inverter heatsink temperature sensor in the outdoor unit. The system has detected either an open circuit or a short circuit in the sensor or its wiring. This causes the unit to stop operating in order to protect the inverter module from potential thermal damage.
Is it safe to keep running my LG air conditioner with error code 65?
No, the unit should not be operated while this error is active. The inverter heatsink temperature sensor exists to protect the inverter module from overheating, and without a reliable sensor reading, the control board cannot apply thermal protection. Continued operation could result in inverter damage that is significantly more costly to repair.
How much does it cost to repair error code 65 on an LG air conditioner?
Repair costs depend on the root cause. If only the sensor connector needs reseating or cleaning, the cost may be limited to a service call fee, typically in the range of $75 to $150. Replacing the heatsink temperature sensor generally costs between $100 and $250 including parts and labor. If the outdoor unit control board has failed, costs can range from $300 to $600 or more depending on the model.
Can I fix error code 65 on my LG air conditioner myself?
A knowledgeable DIYer can inspect and reseat the sensor connector in the outdoor unit as a first step, since a loose connection is one of the most common causes. However, testing sensor resistance and tracing wiring faults requires a multimeter and comfort working inside the outdoor unit with power disconnected. Replacing the control board or sensor wiring is best handled by a qualified technician.
Will resetting the LG air conditioner clear error code 65?
A power reset may temporarily clear the error and allow the unit to restart, but the code will return if the underlying sensor or wiring fault has not been corrected. Resetting without addressing the cause does not resolve the problem and may allow repeated fault conditions. A proper repair requires diagnosing and fixing the sensor circuit.

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