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Error code reference

Samsung Air Conditioner Error Code YEL_ON_RED_ON

Heatsink sensor error

Samsung codesSamsung air conditioner codes

Heatsink sensor error

First step from the service manual

Check IPM module PIN#24,25 solder condition for cracks or short circuits

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

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What YEL_ON_RED_ON means on a Samsung air conditioner

The YEL_ON_RED_ON error code on a Samsung air conditioner indicates a heatsink sensor error within the inverter drive system. The heatsink sensor monitors the temperature of the Intelligent Power Module (IPM), which is the component responsible for converting and regulating power to the compressor. When the sensor detects an abnormal reading, either due to a faulty sensor, wiring issue, or a problem with the IPM itself, the system triggers this fault code to protect the unit from thermal damage or electrical failure.

The primary diagnostic focus is on the IPM module, specifically pins 24 and 25, which carry the heatsink temperature sensor signal. Poor solder joints at these pins are a known cause of this fault. Hairline cracks in the solder can create intermittent or complete open circuits, causing the controller to receive no signal or an out-of-range signal from the sensor. Short circuits at these pins can similarly corrupt the sensor reading and trigger the error. Careful visual inspection under magnification and continuity testing at these points should be the first step in diagnosis.

Beyond solder joint integrity, the heatsink sensor itself may have drifted out of specification or failed entirely. Wiring and connector integrity between the sensor and the IPM board should also be evaluated. In some cases, actual overheating of the heatsink due to blocked airflow, dirty coils, or a failing fan can cause the sensor to report legitimate over-temperature conditions, which the control system flags in the same manner as a sensor fault.

Source: manufacturer service documentation.

Common causes of YEL_ON_RED_ON

  1. 01

    Cracked or faulty solder joints at IPM pins 24 and 25

    Wiring / connection

    Hairline cracks in the solder at IPM module pins 24 and 25 can break the sensor signal circuit, causing the controller to register a heatsink sensor fault. Inspect these joints closely under magnification for cracks, cold solder, or lifting.

  2. 02

    Short circuit at IPM module pins 24 or 25

    Wiring / connection

    A short between pins 24 and 25 or to adjacent traces can corrupt the sensor signal and trigger this error. Check for solder bridges, debris, or damaged traces in this area of the board.

  3. 03

    Failed heatsink temperature sensor

    Part replacement

    The heatsink sensor itself may have failed or drifted outside its specified resistance range, causing the controller to flag an invalid reading. Testing the sensor resistance at operating temperature can confirm failure.

  4. 04

    Wiring or connector damage between sensor and IPM board

    Wiring / connection

    Damaged wiring, corroded connector pins, or a loose harness connection between the heatsink sensor and the IPM board can interrupt the sensor signal. Inspect the full wiring run for chafing, corrosion, or disconnection.

  5. 05

    Actual heatsink overheating due to restricted airflow

    Wiring / connection

    If airflow across the heatsink is blocked by dirt buildup, a failing fan, or obstructed vents, the sensor may be reporting a legitimate over-temperature condition rather than a sensor fault. Check fan operation and clean the heatsink fins before assuming sensor failure.

See the test procedure for each cause

Frequently asked questions about YEL_ON_RED_ON

What does YEL_ON_RED_ON mean on a Samsung air conditioner?
YEL_ON_RED_ON indicates a heatsink sensor error in the inverter drive system. The controller has detected an abnormal or missing signal from the temperature sensor located on the IPM module heatsink. The unit shuts down to prevent potential thermal or electrical damage until the fault is resolved.
Can I fix the YEL_ON_RED_ON error myself?
Some causes, such as restricted airflow or a dirty heatsink, can be addressed without specialized tools. However, diagnosing and repairing solder joint cracks at IPM module pins 24 and 25 requires electronics experience, soldering equipment, and comfort working with inverter-driven power circuits. Most homeowners should have a qualified technician handle this repair due to the high-voltage components involved.
Is it safe to keep running my Samsung air conditioner with the YEL_ON_RED_ON error?
No, you should not continue operating the unit while this error is active. The heatsink sensor is a protective component, and bypassing or ignoring this fault could allow the IPM module to overheat without any thermal protection. This risks permanent damage to the inverter board and compressor, and in severe cases could create a fire or electrical hazard.
How much does it cost to repair the YEL_ON_RED_ON error on a Samsung air conditioner?
Repair costs depend on the root cause. If the issue is a cracked solder joint that can be reflowed, labor costs may range from $75 to $200. If the IPM module or heatsink sensor requires replacement, parts and labor combined could range from $200 to $600 or more depending on the specific unit and local service rates.
Will resetting my Samsung air conditioner clear the YEL_ON_RED_ON error?
A power reset may temporarily clear the error code and allow the unit to restart, but if the underlying fault, such as a cracked solder joint, failed sensor, or blocked airflow, is still present, the code will return. Resetting without diagnosing and correcting the cause is not a permanent fix and can allow the problem to worsen over time.

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