Samsung Air Conditioner Error Code YEL_ON_GRN_FLICKER

This code indicates an outdoor ambient temperature sensor error, specifically an open or short circuit condition in the sensor circuit. The outdoor sensor is a thermistor that the control board uses to monitor outside air temperature for compressor and defrost control. When the board cannot read a valid resistance signal from the sensor, it triggers this fault and may limit system operation. The flickering LED pattern on the outdoor unit is how Samsung's diagnostic system communicates this specific fault.

Operating the system with a faulty outdoor temperature sensor is not recommended. The control board relies on this data for compressor protection and defrost timing, and running without accurate temperature input can lead to inefficient operation or potential compressor damage over time. The system may also limit its own operation automatically as a protective measure when this fault is active.

A power reset may temporarily clear the fault code if the condition was caused by a momentary glitch or brief moisture contact, but if the underlying sensor or wiring problem still exists the error will return quickly. Resetting without repairing the root cause does not fix the problem and can mask the fault long enough for further damage to occur. Diagnostic testing of the sensor resistance should be performed before relying on a reset as a solution.

A knowledgeable DIYer can perform initial diagnostics by visually inspecting the outdoor sensor wiring and connector for damage or corrosion, and by measuring sensor resistance with a multimeter. However, if the sensor requires replacement or the fault involves the control board, working inside the outdoor unit requires caution around capacitors that hold a dangerous charge. If you are not experienced with electrical diagnostics on HVAC equipment, having a certified technician handle the repair is the safer choice.

If the repair only requires cleaning or reseating a corroded connector, the cost is typically limited to a service call fee, generally in the range of $75 to $150. Replacing the outdoor temperature sensor itself is usually an affordable repair, with parts typically costing $20 to $60 and total repair costs ranging from $100 to $250 including labor. If the outdoor control board needs replacement, costs can rise significantly, often falling in the $300 to $600 range depending on the model.