Samsung Air Conditioner Error Code E266

Error code E266 on a Samsung air conditioner indicates that the top sensor of compressor 1 has become detached or is no longer making proper contact with the compressor body. This sensor is a thermistor mounted at the top of the first compressor in the system, responsible for monitoring the discharge or surface temperature of the compressor during operation. The control board uses this temperature data to protect the compressor from overheating and to regulate system performance. When the sensor signal is lost or falls outside the expected range due to physical detachment, the system generates E266 to alert the technician.

The most common cause of this fault is physical dislodgement of the sensor from its mounting clip or bracket on the compressor housing. Vibration from normal compressor operation can loosen sensor clips over time, especially in systems with high run hours. Wiring harness tension or improper routing can also pull the sensor away from its contact point. In some cases, the sensor wire itself may have been disturbed during previous service work.

Diagnosing E266 begins with a physical inspection of the top sensor on compressor 1. The sensor should be firmly seated against the compressor body and secured by its retaining clip. Check that the wiring harness is not under tension and that the connector at the control board is fully seated. If the sensor is properly attached but the fault persists, the thermistor itself may have failed and will require resistance testing and likely replacement.