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Error code reference

Samsung Air Conditioner Error Code E129

Indoor heat exchanger EVAP OUT sensor dislocation error

Samsung codesSamsung air conditioner codes

Indoor heat exchanger EVAP OUT sensor dislocation error - sensor has been physically dislocated from piping.

First step from the service manual

Check if the out sensor of IU's heat exchanger is dislocated and if the holder is attached.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E129 means on a Samsung air conditioner

Samsung E129 is an indoor heat exchanger EVAP OUT sensor dislocation error. This code activates when the system detects that the evaporator outlet temperature sensor has physically separated from its mounting position on the indoor unit's heat exchanger piping. The EVAP OUT sensor is a thermistor that monitors refrigerant temperature at the outlet point of the evaporator coil, providing the control board with data used to regulate compressor operation, prevent coil icing, and manage airflow. When the sensor loses contact with the pipe it is secured to, it reads ambient air temperature instead of pipe surface temperature, causing the system to receive inaccurate data and triggering this fault.

The sensor is held against the evaporator piping using a plastic or metal clip holder. Over time, this holder can crack, loosen, or detach entirely due to vibration, thermal cycling, or physical contact during filter cleaning or servicing. When the holder fails, the sensor hangs free in the indoor unit cabinet, producing temperature readings that are inconsistent with normal refrigerant behavior. The control board interprets this discrepancy as a sensor displacement event and stops normal operation to protect the system from running on faulty thermal feedback.

Diagnosis begins with a physical inspection of the evaporator outlet area inside the indoor unit. The technician should confirm whether the sensor has separated from the piping and whether the holder clip is still intact, deformed, or missing entirely. If the holder is damaged, it must be replaced to restore proper sensor contact. In some cases, the sensor wire may also have been pulled or kinked during displacement, which requires inspecting the wire harness and connector at the control board for continuity and secure seating.

Source: manufacturer service documentation.

Common causes of E129

  1. 01

    Sensor holder clip detached or broken

    Part replacement

    The plastic or metal clip that secures the EVAP OUT sensor to the evaporator piping has cracked or released, allowing the sensor to hang free. Inspect the sensor mounting point on the outlet pipe for a missing or damaged holder.

  2. 02

    Sensor physically dislodged during servicing

    Wiring / connection

    Routine filter cleaning or coil maintenance can accidentally knock the sensor off the pipe if technicians or homeowners contact the sensor wire or body during access. Check if the sensor is visibly dangling away from the piping.

  3. 03

    Vibration-induced loosening over time

    Part replacement

    Prolonged unit operation causes continuous vibration that can gradually weaken the sensor clip's grip on the pipe. This is more common in older units or those with any pre-existing mounting wear.

  4. 04

    Sensor wire pulled taut causing displacement

    Wiring / connection

    If the sensor wire is routed with insufficient slack, thermal expansion and contraction of the piping can pull the sensor off its mount. Inspect the wire routing for tension and confirm there is adequate slack near the mounting point.

  5. 05

    Defective or failed thermistor after dislocation

    Part replacement

    If the sensor was dislodged and then contacted a sharp edge or sustained a pinch in the wire harness, the thermistor itself may have been damaged and will require replacement even after remounting.

See the test procedure for each cause

Frequently asked questions about E129

What does E129 mean on a Samsung air conditioner?
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.
Can I fix E129 myself without a technician?
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.
Is it safe to keep running the air conditioner when E129 is displayed?
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.
How much does it cost to repair a Samsung E129 error?
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.
Will resetting the air conditioner clear the E129 error code?
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.

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