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Error code reference

Daewoo Air Conditioner Error Code 1 blink (ON lamp)

Room sensor open or short circuit

Daewoo codesDaewoo air conditioner codes

Room sensor open or short circuit — unit continues working with room temperature fixed at 32°C in cooling mode.

First step from the service manual

Check room temperature sensor for open or short condition.

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

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What 1 blink (ON lamp) means on a Daewoo air conditioner

The 1 blink fault on the ON lamp of a Daewoo air conditioner indicates that the room temperature sensor (also called the indoor ambient sensor) has developed an open circuit or short circuit condition. This sensor is a negative temperature coefficient (NTC) thermistor that feeds a continuous resistance signal to the indoor PCB. The control board uses this signal to monitor room temperature and regulate compressor and fan operation accordingly. When the board detects that the resistance has fallen outside its expected range, either dropping near zero (short) or rising to an extreme value (open), it triggers this fault condition.

Rather than shutting the unit down entirely, the Daewoo control logic enters a failsafe mode. In cooling operation, the system substitutes a fixed assumed room temperature of 32°C in place of the missing sensor data. This allows the unit to continue running and providing some level of cooling, but it means the thermostat function is effectively disabled. The unit cannot accurately compare the room temperature against the setpoint, so it will not cycle on and off based on actual conditions.

The room sensor is typically a small thermistor probe located near the air intake grille on the indoor unit. Common failure points include corrosion at the connector pins, physical damage to the sensor wire harness, or degradation of the thermistor element itself due to moisture or age. Because the unit continues operating during this fault, the issue can go unnoticed until the 1 blink code is observed on the ON lamp during a status check.

Source: manufacturer service documentation.

Common causes of 1 blink (ON lamp)

  1. 01

    Faulty or degraded room temperature thermistor

    Part replacement

    The NTC thermistor element itself can fail over time due to moisture exposure, age, or physical stress, causing its resistance to read outside the normal range. Testing the sensor with a multimeter at a known room temperature and comparing the resistance reading to the expected value for that temperature will confirm this failure.

  2. 02

    Loose or corroded sensor connector

    Wiring / connection

    The thermistor connects to the indoor PCB via a small plug connector that can loosen, oxidize, or accumulate debris over time. Inspecting and reseating the connector, or cleaning the pins, can resolve the fault if the thermistor itself tests within spec.

  3. 03

    Damaged sensor wiring harness

    Part replacement

    The wire running from the thermistor to the PCB can become pinched, cut, or broken, particularly during filter cleaning or if the unit has been serviced previously. Visually inspecting the full length of the wire for damage or continuity testing the harness will identify this issue.

  4. 04

    Moisture or contamination on the PCB connector port

    Wiring / connection

    Water ingress into the indoor unit can deposit residue on the sensor connector pins or the PCB header, creating an unintended short or a high-resistance open condition. Drying the area and cleaning the connector contacts may restore normal operation.

  5. 05

    Failed indoor control PCB

    Part replacement

    If the thermistor and its wiring test correctly but the fault persists, the input circuit on the indoor PCB responsible for reading the sensor signal may have failed. This is less common but should be considered after ruling out the sensor and wiring.

See the test procedure for each cause

Frequently asked questions about 1 blink (ON lamp)

What does 1 blink (ON lamp) mean on a Daewoo air_conditioner?
A single blink of the ON lamp on a Daewoo air conditioner signals that the room temperature sensor has been detected in an open or short circuit condition. The indoor control board is no longer receiving a valid resistance signal from the thermistor and cannot accurately measure room temperature. In response, the unit enters a failsafe mode and assumes a fixed room temperature of 32 degrees Celsius while continuing to run in cooling mode. The fault code will remain active until the sensor fault is diagnosed and corrected.
Can I fix the 1 blink (ON lamp) fault on my Daewoo air conditioner myself?
A knowledgeable DIYer can perform initial diagnostics such as inspecting the sensor connector for looseness or corrosion and reseating it, which sometimes resolves the fault. Testing the thermistor with a multimeter to check its resistance is also within reach for someone comfortable with basic electronics. However, if the sensor itself needs replacement or the indoor PCB is involved, those repairs are generally better handled by a qualified technician who can source the correct sensor and safely access the internal components.
Is it safe to keep running my Daewoo air conditioner while it shows the 1 blink error?
The unit is designed to continue operating in this fault state, so it is not an immediate safety hazard. However, because the system is using a fixed assumed temperature of 32 degrees Celsius rather than the actual room temperature, it cannot regulate cooling accurately or cycle based on your thermostat setting. Running the unit in this condition for an extended period could result in inadequate temperature control and potentially greater energy use, so the fault should be addressed in a timely manner.
Will resetting my Daewoo air conditioner clear the 1 blink error?
A power reset may temporarily clear the displayed fault, but if the room temperature sensor is genuinely open or shorted, the fault will return once the control board performs its sensor checks again. Resetting the unit does not repair the underlying sensor or wiring problem. A lasting resolution requires physically inspecting and testing the sensor, its connector, and the associated wiring to find and correct the root cause.
How much does it cost to repair the room temperature sensor fault on a Daewoo air conditioner?
Repair costs vary depending on whether the issue is a connector problem, a failed thermistor, or a faulty PCB. A replacement NTC thermistor sensor is generally an inexpensive part, typically in the range of a few dollars to around 20 to 40 dollars depending on availability. When labor is included, a professional service call to diagnose and replace the sensor can range from roughly 80 to 200 dollars or more. PCB replacement, if required, would add significantly to that cost.

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