Samsung Heat Pump Error Code E519

E519 indicates a COND MID temperature sensor error on the outdoor unit heat exchanger. The control board has detected either an open circuit or a short circuit from the condenser midpoint thermistor, which monitors coil temperature during operation. The system flags this fault to prevent operating with unreliable thermal data.

Continuing to operate the unit with E519 active is not recommended. The COND MID sensor provides temperature data the system uses to protect the heat exchanger and compressor. Running without accurate sensor feedback could allow conditions that damage the compressor or refrigerant circuit, leading to a much more costly repair.

Resetting the heat pump may temporarily clear the E519 code, but if the underlying sensor fault is still present, the error will return once the system restarts and polls the sensor again. A reset is only a lasting fix if the cause was a transient connector issue that was corrected before the reset. The sensor and wiring should be inspected and tested to confirm the fault is genuinely resolved.

A homeowner comfortable working around outdoor HVAC equipment can check whether the sensor connector has simply come loose from the PCB, which requires no tools or parts. However, measuring thermistor resistance and replacing a faulty sensor or wiring harness on a heat pump outdoor unit is best handled by a qualified technician, particularly because the refrigerant circuit and high-voltage components are located in the same enclosure.

If the fix is a reseated connector, the cost is limited to a service call fee, typically in the range of $75 to $150. Replacing the COND MID thermistor sensor itself is generally a low-cost part, with the total repair including labor usually falling between $100 and $300. If the outdoor PCB needs replacement, costs can rise significantly, often ranging from $300 to $600 or more depending on the model.