LG Heat Pump Error Code P782

P782 on an LG heat pump indicates that the system has restricted cooling mode operation because the outdoor temperature has been detected at or below -5°C (23°F). This is a built-in protective control function, not a component failure. The unit will not run in cooling mode under these conditions to prevent damage to the refrigeration system. If the outdoor temperature is actually warmer than -5°C, the outdoor temperature sensor may need to be inspected.

P782 itself is a safety and protection feature, not a warning of a dangerous condition. The system is actively preventing operation that could harm the compressor or refrigerant circuit. If the code is appearing incorrectly due to a faulty sensor, there is no immediate safety hazard to occupants, but the unit will not cool until the issue is resolved.

If the code is simply due to cold weather, there is no repair cost at all. If an outdoor ambient temperature sensor replacement is needed, parts and labor typically range from around $75 to $200 depending on the model and local service rates. Control board replacement, if required, would be a higher cost repair generally ranging from $250 to $600 or more.

First, confirm the actual outdoor temperature using an independent thermometer. If the temperature is genuinely below -5°C, no fix is needed as the restriction is intentional and will clear once temperatures rise. If the outdoor temperature is above -5°C and the code persists, inspect the outdoor ambient temperature sensor and its wiring for faults, incorrect resistance, or damaged connectors.

A manual reset will not permanently clear P782 if the underlying condition still exists. If the outdoor temperature remains below -5°C, the restriction will reactivate immediately after a reset. If the code is caused by a faulty temperature sensor, the code will return until the sensor or wiring issue is repaired.