Samsung Air Conditioner Error Code 291

Error code 291 on a Samsung air conditioner indicates a high pressure sensor error caused by an open or short circuit condition. A short error occurs when the sensor signal voltage drops below 0.4V, and an open error occurs when the voltage exceeds 4.2V. The unit stops operating to protect the refrigerant system and compressor. The fault is most often related to wiring, connector, or sensor issues rather than an actual refrigerant pressure problem.

No, you should not continue operating the unit while error code 291 is active. The high pressure sensor protects the compressor and refrigerant circuit from dangerous over-pressure conditions. With the sensor circuit faulted, the system cannot monitor pressure reliably, which removes an important safety safeguard. Keep the unit off until the fault is diagnosed and repaired.

A power reset may temporarily clear the error from the display, but the code will return if the underlying wiring or sensor fault is still present. Because the error is caused by an electrical circuit condition rather than a temporary operating glitch, resetting the unit does not fix the problem. A proper diagnosis of the high pressure sensor circuit is needed before the error will stay cleared.

Some basic checks are within reach for a knowledgeable DIYer, such as inspecting the high pressure sensor wiring harness for obvious breaks, loose connectors, or corrosion. However, testing the sensor output voltage and working around refrigerant system components generally requires proper tools and technical knowledge. If wiring inspection does not resolve the issue, a qualified HVAC technician should complete the diagnosis and repair.

Repair costs vary depending on whether the fix involves only wiring or connector work versus sensor or control board replacement. Wiring repairs and connector cleaning are typically lower cost, often in the range of $75 to $200 for labor. High pressure sensor replacement, including parts and labor, generally falls in the $150 to $400 range. Control board replacement, if required, can be more expensive depending on the model.