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Error code reference

Samsung Air Conditioner Error Code t4

Liquid refrigerant pipe (COND OUT) temperature sensor error (OPEN/SHORT)

Samsung codesSamsung air conditioner codes

Liquid refrigerant pipe (COND OUT) temperature sensor error (OPEN/SHORT) - error level: over 4.9V (-50°C), below 0.4V (93°C).

First step from the service manual

Check if sensor connector is departed from PCB; measure resistance across both terminals.

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

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What t4 means on a Samsung air conditioner

The T4 error code on a Samsung air conditioner indicates a fault in the liquid refrigerant pipe temperature sensor, specifically the condenser outlet (COND OUT) sensor. This thermistor monitors the temperature of the refrigerant as it exits the condenser coil in liquid form. The PCB uses the voltage signal from this sensor to calculate refrigerant temperature and adjust system operation accordingly. The error is triggered when the sensor signal voltage falls outside the acceptable operating range: a reading above 4.9V corresponds to an open circuit condition (indicating a temperature below -50 degrees C), while a reading below 0.4V indicates a short circuit condition (indicating a temperature above 93 degrees C).

This type of fault is categorized as either an OPEN or SHORT error. An open circuit means the signal path is broken, causing the PCB to see an abnormally high voltage. A short circuit means the sensor signal wire is contacting ground or another conductor, pulling the voltage down below the minimum threshold. Both conditions cause the PCB to lose reliable temperature data for that refrigerant circuit point, which can prevent the unit from operating safely.

The first diagnostic step is to inspect the sensor connector at the PCB for any signs of disconnection or corrosion, then measure resistance across both sensor terminals. A properly functioning NTC thermistor will show a resistance value that corresponds to the ambient or pipe temperature at the time of measurement. Readings of zero ohms or open circuit (infinite resistance) confirm a faulty sensor. If resistance appears normal, the wiring harness and PCB input circuit should be inspected next.

Source: manufacturer service documentation.

Common causes of t4

  1. 01

    Disconnected sensor connector

    Wiring / connection

    The sensor connector may have vibrated loose from the PCB or sensor harness plug. Visually inspect the connector at the board and at the sensor body for any separation or loose fit.

  2. 02

    Failed temperature sensor (open circuit)

    Part replacement

    The thermistor element inside the sensor can fail open, causing voltage at the PCB input to rise above 4.9V. Resistance measured across the sensor terminals will read infinite or out of range for the current pipe temperature.

  3. 03

    Short circuit in sensor or wiring

    Part replacement

    A pinched, chafed, or damaged wire in the sensor harness can create a short to ground, pulling the signal voltage below 0.4V. Inspect the wiring run from the sensor to the PCB for any visible damage or contact with sharp edges.

  4. 04

    Corroded or contaminated connector pins

    Wiring / connection

    Moisture intrusion into the connector can cause corrosion on the sensor or PCB-side pins, increasing resistance unpredictably or creating intermittent open conditions. Clean and inspect the connector pins closely for oxidation or debris.

  5. 05

    Faulty PCB sensor input circuit

    Part replacement

    If the sensor and wiring both test within normal resistance parameters, the PCB input circuit itself may have failed, misreading a good sensor signal. This is the least common cause and is diagnosed after the sensor and harness are confirmed good.

See the test procedure for each cause

Frequently asked questions about t4

What does t4 mean on a Samsung air conditioner?
The T4 error code indicates a fault with the liquid refrigerant pipe temperature sensor at the condenser outlet, also called the COND OUT sensor. The unit has detected that the sensor signal voltage is either too high (above 4.9V, indicating an open circuit) or too low (below 0.4V, indicating a short circuit). This prevents the system from accurately monitoring refrigerant conditions at that point in the circuit.
Can I fix the T4 error code myself?
A homeowner with basic electrical knowledge can check whether the sensor connector has simply come loose from the PCB, which is the most straightforward fix. However, measuring sensor resistance and diagnosing wiring faults requires a multimeter and some familiarity with HVAC electronics. Replacing the sensor or PCB is best handled by a qualified HVAC technician, particularly because the refrigerant system is involved.
Is it safe to run my Samsung air conditioner with the T4 error active?
It is generally not recommended to continue running the unit while the T4 error is active. Without accurate condenser outlet temperature data, the control board cannot properly manage refrigerant flow and system protection functions. Continued operation could potentially lead to additional component stress or further faults.
How much does it cost to repair a T4 error on a Samsung air conditioner?
Repair costs depend on the root cause. A loose connector costs nothing beyond a service call, which typically runs between 75 and 150 dollars. A sensor replacement part is generally inexpensive, often in the range of 15 to 60 dollars, but labor charges for diagnosis and replacement can bring the total to between 100 and 250 dollars. PCB replacement is significantly more expensive, potentially ranging from 200 to 500 dollars or more depending on the model.
Will resetting the air conditioner clear the T4 error code?
Resetting the unit may temporarily clear the code from the display, but the error will return if the underlying sensor fault is still present. A reset does not repair a failed sensor, broken wire, or faulty connector. Proper diagnosis and repair of the root cause is necessary to resolve the T4 error permanently.

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