Samsung Heat Pump Error Code E129

E129 indicates a suction temperature sensor breakaway fault. The system detected that the suction line temperature did not change by at least 2°C during the first 30 minutes after the compressor started. This typically points to the sensor being detached from the pipe, a failed sensor thermistor, or a wiring problem in the sensor circuit.

Continuing to operate the unit with an active E129 fault is not recommended. The suction temperature sensor provides data the control board uses to protect the compressor from operating outside safe parameters. Running the system without a functioning sensor risks potential compressor damage, which is significantly more costly to repair than addressing the sensor fault.

If the fix is simply reattaching a dislodged sensor to its holder, there may be little to no parts cost, with only a service call fee to pay. If the sensor thermistor has failed and needs replacement, parts and labor typically range from around $100 to $300 depending on the technician and region. If the fault is related to a refrigerant issue, additional costs for refrigerant service will apply.

Start by powering down the unit and checking that the suction temperature sensor and its holder are firmly attached to the suction line. If the sensor is properly mounted, use a multimeter to test the sensor resistance and inspect the wiring harness for damage or corroded connectors. If the sensor has failed, it will need to be replaced. A qualified technician should also check the refrigerant charge if the sensor and wiring test out as good.

A power reset may temporarily clear the fault and allow the unit to restart, but if the underlying cause such as a detached sensor or failed thermistor is not corrected, the error will return within 30 minutes of the next compressor start. The fault code should be resolved at its source rather than relying on repeated resets.