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Error code reference

Samsung Air Conditioner Error Code YEL_ON_GRN_FLICKER

Outdoor sensor error (open/short)

Samsung codesSamsung air conditioner codes

Outdoor sensor error (open/short)

First step from the service manual

Check outdoor temperature sensor resistance

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

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What YEL_ON_GRN_FLICKER means on a Samsung air conditioner

The YEL_ON_GRN_FLICKER error code on a Samsung air conditioner indicates a fault with the outdoor ambient temperature sensor. This sensor is a negative temperature coefficient (NTC) thermistor responsible for monitoring the outdoor air temperature and feeding that data to the control board. The control board uses this information to regulate compressor operation, defrost cycles, and overall system efficiency. When the board detects that the sensor signal is either absent or out of the expected resistance range, it flags this open or short circuit condition and displays the fault through the yellow-on-green flickering LED pattern.

An open circuit fault occurs when the sensor or its wiring has a break, causing resistance to read as infinite or beyond the acceptable threshold. A short circuit fault is the opposite condition, where resistance drops near zero due to a wiring fault or sensor failure. In either case, the control board cannot trust the temperature data and may limit or halt operation to protect the system. The first diagnostic step is to measure the outdoor temperature sensor resistance with a multimeter and compare it against the temperature-resistance curve specified for the unit.

Common causes include physical damage to the sensor from weather exposure, corrosion at the connector terminals, pinched or chafed wiring in the outdoor unit, and outright thermistor failure due to age. The sensor is typically mounted on the outdoor coil assembly or within the outdoor unit air inlet area. Connector corrosion is especially common in coastal or high-humidity environments and can cause intermittent resistance readings that trigger the fault even when the sensor itself is still functional.

Source: manufacturer service documentation.

Common causes of YEL_ON_GRN_FLICKER

  1. 01

    Failed outdoor temperature sensor (thermistor)

    Part replacement

    The NTC thermistor itself has degraded or failed, producing resistance values outside the acceptable range for any given temperature. Measuring resistance across the sensor leads and finding an open line or near-zero reading confirms this failure.

  2. 02

    Corroded or loose sensor connector

    Wiring / connection

    Moisture and oxidation at the sensor wiring harness connector can increase contact resistance or break the circuit intermittently. Inspect the connector on the outdoor unit control board side and at the sensor plug for green or white corrosion and clean or replace as needed.

  3. 03

    Damaged sensor wiring

    Part replacement

    The wiring between the sensor and the control board can be pinched, chafed, or cut by vibration, rodents, or improper installation. Visually trace the sensor wire through the outdoor unit and check for insulation damage or breaks.

  4. 04

    Water intrusion into sensor or connector

    Wiring / connection

    Direct water exposure from rain or condensate can short the sensor leads or fill the connector housing. Inspect the sensor housing and connector for moisture and dry thoroughly before re-testing resistance.

  5. 05

    Faulty outdoor unit control board

    Part replacement

    If the sensor and all wiring test within specification but the fault persists, the outdoor control board's sensor input circuit may have failed. This is the least common cause and should only be considered after the sensor and wiring are confirmed good.

See the test procedure for each cause

Frequently asked questions about YEL_ON_GRN_FLICKER

What does YEL_ON_GRN_FLICKER mean on a Samsung air_conditioner?
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.
Can I fix the YEL_ON_GRN_FLICKER error myself?
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.
Is it safe to keep running my air conditioner with the YEL_ON_GRN_FLICKER error?
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.
How much does it cost to repair the YEL_ON_GRN_FLICKER error on a Samsung air conditioner?
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.
Will resetting my Samsung air conditioner clear the YEL_ON_GRN_FLICKER error?
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.

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