Samsung Air Conditioner Error Code OPERATION_TIMER_FLICKER

This error code indicates that the indoor unit heat exchanger temperature sensor has been detected as either open or shorted by the control board. The sensor monitors coil temperature to regulate the refrigerant cycle, and when its signal falls outside the expected range, the unit stops operating and the operation and timer lights begin to flicker. The fault is diagnosed by checking the sensor resistance at connector CN43 on the indoor PCB.

When this error is active, the unit will generally shut down or refuse to operate normally as a protective measure. Attempting to force the unit to run without a functional heat exchanger sensor could result in improper refrigerant regulation and potential damage to the compressor or other components. It is best to leave the unit off until the sensor fault is resolved.

Power cycling the unit may temporarily clear the error display, but the fault will return as soon as the control board polls the sensor again and detects the abnormal resistance reading. A reset does not resolve the underlying hardware problem with the sensor or wiring. The error will continue to recur until the faulty component is repaired or replaced.

A knowledgeable DIYer can inspect the wiring harness for visible damage and clean the CN43 connector if corrosion is present. Measuring sensor resistance with a multimeter is also straightforward if you are comfortable working with low-voltage electronics. However, replacing the thermistor or indoor PCB typically requires disassembling the indoor unit, so many homeowners prefer to have a certified technician handle this repair.

If only the indoor heat exchanger temperature sensor needs replacement, parts and labor typically range from around $80 to $200 depending on the model and local labor rates. If the fault turns out to be a failed indoor PCB, costs can range from $150 to $400 or more. Cleaning a corroded connector is generally the least expensive fix and may fall within a standard diagnostic service call fee.