Samsung Air Conditioner Error Code E129

E129 indicates that the evaporator outlet temperature sensor inside the indoor unit has physically separated from its mounting position on the heat exchanger piping. The sensor relies on direct contact with the pipe to read accurate refrigerant temperatures. Without that contact, the control board receives incorrect data and shuts the unit down. This is a sensor displacement fault, not an electrical failure of the sensor itself in most cases.

The unit will typically stop normal operation when E129 is active, which is a protective measure. Attempting to force the unit to run while the sensor is displaced can cause the system to operate without accurate coil temperature monitoring, potentially leading to evaporator icing or compressor stress. It is best to leave the unit off until the sensor is properly remounted.

A power reset will temporarily clear the displayed code, but E129 will return immediately once the unit restarts and the control board detects that the sensor is still not properly seated against the piping. The fault condition must be physically corrected by remounting or replacing the sensor and its holder before the error will stay cleared.

If you are comfortable accessing the inside of the indoor unit, you can inspect whether the EVAP OUT sensor is visibly hanging away from the evaporator piping and attempt to reseat it into its holder clip. However, if the holder clip is broken or the sensor wire is damaged, replacement parts are needed and the repair is best handled by a qualified technician. Improper reassembly can cause recurring faults or new errors.

If the sensor holder simply needs to be reseated with no parts required, the repair cost is primarily a service call fee, typically in the range of $75 to $150 depending on your region. If the sensor clip or thermistor needs replacement, total parts and labor costs generally fall between $100 and $250. Prices vary based on technician rates and part availability.