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Error code reference

Daewoo Air Conditioner Error Code ON lamp continuous blink

Room sensor open or short circuit

Daewoo codesDaewoo air conditioner codes

Room sensor open or short circuit — unit continuously works but fixes room temperature to 32°C in heating mode.

First step from the service manual

Check room temperature sensor for open or short circuit. Micom input voltage 0~0.3V indicates open, 4.7~5.0V indicates short.

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

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What ON lamp continuous blink means on a Daewoo air conditioner

The ON lamp continuous blink code on a Daewoo air conditioner indicates a fault with the room temperature sensor, specifically an open or short circuit condition in that sensor circuit. The room temperature sensor is a thermistor responsible for feeding ambient temperature data to the micom (microcontroller). When the micom detects an abnormal input voltage from this sensor, it triggers the continuous blink pattern to alert the technician to a measurement failure. Despite the fault, the unit does not shut down entirely. Instead, it continues operating in heating mode but defaults to a fixed setpoint of 32°C, since it can no longer receive accurate ambient temperature feedback.

The key diagnostic reference for this fault is the micom input voltage reading from the sensor circuit. A reading of 0 to 0.3V at the micom input indicates an open circuit condition, meaning the signal path is broken. This typically points to a disconnected connector, a broken wire, or a failed thermistor with infinite resistance. A reading of 4.7 to 5.0V indicates a short circuit condition, where the signal line is being pulled toward the supply voltage. This can result from a shorted thermistor, damaged wiring insulation causing a short to voltage, or a failed micom input circuit.

The room temperature sensor itself is a negative temperature coefficient (NTC) thermistor. Under normal operating conditions, its resistance changes inversely with temperature, and the micom reads a corresponding mid-range voltage. Any deviation to the extreme ends of the 0 to 5V reference range signals a circuit integrity problem rather than an actual temperature reading, prompting the fault indication.

Source: manufacturer service documentation.

Common causes of ON lamp continuous blink

  1. 01

    Failed room temperature thermistor

    Part replacement

    The NTC thermistor itself has failed internally, causing either an open circuit (very high or infinite resistance) or a short circuit (near-zero resistance). This is the most common cause and is confirmed by measuring the sensor resistance directly and comparing it to the expected value for the current room temperature.

  2. 02

    Disconnected or loose sensor connector

    Wiring / connection

    The connector linking the room temperature sensor to the control board may have vibrated loose or been inadvertently disconnected. Inspect the connector at both the sensor and the board for secure seating and signs of corrosion.

  3. 03

    Damaged sensor wiring

    Part replacement

    The wiring between the thermistor and the micom board may have a break or damaged insulation, resulting in an open or short circuit. Visually inspect the wire harness for pinching, chafing, or burn marks and use a multimeter to check continuity.

  4. 04

    Corrosion or moisture at the sensor connector

    Wiring / connection

    Moisture ingress into the sensor connector can cause resistance changes or short circuits that mimic sensor failure. Check the connector pins for oxidation or water residue, which can pull the micom input voltage toward an out-of-range value.

  5. 05

    Faulty micom or control board input circuit

    Part replacement

    In less common cases, the micom board itself has a failed input stage that causes it to read the sensor voltage incorrectly, even when the sensor and wiring are intact. This should be considered only after the sensor and wiring have been confirmed good.

See the test procedure for each cause

Frequently asked questions about ON lamp continuous blink

What does ON lamp continuous blink mean on a Daewoo air_conditioner?
The ON lamp continuous blink code means the micom has detected an open or short circuit in the room temperature sensor circuit. Because the unit cannot get a valid temperature reading, it defaults to running heating mode at a fixed 32°C rather than shutting down completely. The micom input voltage is used to distinguish between an open circuit (0 to 0.3V) and a short circuit (4.7 to 5.0V), which helps direct the repair to either the sensor, wiring, or connectors.
How do I fix the ON lamp continuous blink error on my Daewoo air conditioner?
Start by measuring the micom input voltage from the room temperature sensor circuit. A reading below 0.3V points to an open circuit, while a reading above 4.7V indicates a short. Check the sensor connector for loose pins or corrosion, inspect the wiring for damage, and test the thermistor resistance directly. If the sensor has failed, replacing it should clear the fault once the circuit returns to its normal operating range.
Is it safe to keep running my Daewoo air conditioner while the ON lamp is continuously blinking?
The unit will continue to operate in heating mode at a fixed 32°C despite the fault, so it is not completely non-functional. However, running it in this state means there is no accurate temperature control, and the unit may overheat a space or run continuously without cycling properly. It is advisable to address the sensor fault promptly to restore normal temperature regulation.
How much does it cost to repair the ON lamp continuous blink fault on a Daewoo air conditioner?
If only the room temperature sensor needs replacement, parts costs are typically in the range of $10 to $40 depending on the specific sensor and availability. If a technician is needed for diagnosis and repair, total service costs including labor generally range from $75 to $200. Control board replacement, if required, would cost more, typically in the $100 to $300 range for parts alone.
Will resetting my Daewoo air conditioner clear the ON lamp continuous blink error?
A power reset will not permanently clear this fault because the underlying sensor circuit problem remains. The micom will detect the abnormal input voltage again on startup and resume the blink pattern. The error will only clear once the room temperature sensor circuit is repaired and the micom input voltage returns to its normal mid-range operating level.

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