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Error code reference

Samsung Air Conditioner Error Code TIMER_FLICKER

Indoor unit room temperature sensor error (open/short)

Samsung codesSamsung air conditioner codes

Indoor unit room temperature sensor error (open/short)

First step from the service manual

Check indoor temperature sensor resistance at connector CN43

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

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What TIMER_FLICKER means on a Samsung air conditioner

The TIMER_FLICKER error on a Samsung air conditioner indicates a fault with the indoor unit room temperature sensor (also called the return air thermistor). This sensor is a negative temperature coefficient (NTC) thermistor that continuously monitors the ambient air temperature entering the indoor unit. The control board uses this reading to regulate compressor operation, fan speed, and overall system cycling. When the board detects a reading outside the expected resistance range, it flags the fault and displays TIMER_FLICKER through a flickering timer LED on the indoor unit panel.

The error specifically indicates either an open circuit or a short circuit condition in the sensor circuit. An open circuit occurs when the thermistor resistance rises beyond the board's acceptable upper threshold, often caused by a broken sensor element, a disconnected connector, or damaged wiring. A short circuit occurs when resistance drops below the lower threshold, typically due to moisture intrusion into the connector, a pinched wire, or internal sensor failure. The first diagnostic step is to measure the sensor resistance directly at connector CN43 on the indoor unit PCB and compare the reading against the temperature-resistance table for that sensor type.

Because the room temperature sensor is critical for accurate temperature control, the system will not operate normally with this fault active. Technicians should inspect the wiring harness between the sensor and CN43 for visible damage, corrosion, or loose pin connections before condemning the sensor itself. If wiring checks out, the sensor should be replaced and the unit retested to confirm the fault clears.

Source: manufacturer service documentation.

Common causes of TIMER_FLICKER

  1. 01

    Failed room temperature thermistor

    Part replacement

    The NTC thermistor element itself has failed internally, producing a resistance reading that is either too high (open) or too low (short) for the control board to accept. This is the most frequent cause and is confirmed by measuring resistance at CN43 and finding a value outside the expected range for the current ambient temperature.

  2. 02

    Disconnected or loose connector at CN43

    Wiring / connection

    The sensor connector at CN43 on the indoor PCB may have worked loose due to vibration or improper reassembly after a previous service. Inspect the connector for full seating and check each pin for bent or retracted terminals.

  3. 03

    Damaged sensor wiring harness

    Part replacement

    The wire leads running from the thermistor to the CN43 connector can become pinched, cut, or abraded inside the indoor unit, causing an intermittent or permanent open circuit. Trace the full length of the harness and flex it gently while monitoring for resistance changes.

  4. 04

    Moisture or corrosion in the connector

    Wiring / connection

    Water ingress from condensation or a drain issue can corrode the CN43 connector pins, increasing contact resistance or causing a short between pins. Look for discoloration, white deposits, or moisture inside the connector housing.

  5. 05

    Faulty indoor control PCB

    Part replacement

    If the thermistor and all wiring measure within spec but the error persists, the indoor board's sensor input circuit may have failed. This is the least likely cause and should only be considered after all sensor and wiring checks are completed.

See the test procedure for each cause

Frequently asked questions about TIMER_FLICKER

What does TIMER_FLICKER mean on a Samsung air conditioner?
TIMER_FLICKER indicates a fault with the indoor unit room temperature sensor, detected as either an open or short circuit condition. The control board monitors the NTC thermistor at connector CN43 and triggers this error when the resistance reading falls outside the acceptable range. The unit cannot regulate cooling properly while this fault is active, so normal operation is suspended until the issue is resolved.
Can I fix the TIMER_FLICKER error myself?
A knowledgeable DIYer can check the sensor connector at CN43 for loose connections and inspect the wiring harness for visible damage without specialized tools. Measuring thermistor resistance with a multimeter and comparing it to the expected value for the current room temperature is also within reach for someone comfortable working inside the indoor unit. However, if the PCB or refrigerant system is involved, a licensed HVAC technician should handle the repair.
Is it safe to keep running my Samsung air conditioner with the TIMER_FLICKER error?
Running the unit with an active TIMER_FLICKER fault is not recommended. Without a functioning room temperature sensor, the control board cannot accurately regulate system operation, which can lead to improper cycling, reduced efficiency, or potential stress on other components. It is best to address the fault before returning the unit to regular use.
How much does it cost to repair the TIMER_FLICKER error on a Samsung air conditioner?
If only the room temperature thermistor needs replacement, parts typically cost between $10 and $40 depending on the model, with labor adding $75 to $150 for a professional service call. If the indoor PCB has failed, the repair cost rises considerably, often ranging from $150 to $350 or more including parts and labor. Getting a diagnostic visit first will help confirm exactly which component needs replacement.
Will resetting my Samsung air conditioner clear the TIMER_FLICKER error?
A power reset may temporarily clear the error display, but the fault will return almost immediately if the underlying sensor or wiring problem has not been corrected. The control board will re-detect the out-of-range resistance at CN43 as soon as it performs its next sensor check. A permanent fix requires repairing or replacing the faulty component rather than relying on resets.

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