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Error code reference

Daewoo Air Conditioner Error Code ON LAMP 1 blink (8s interval)

Indoor coil sensor open or short, or outdoor coil sensor open or short; unit does not work.

Daewoo codesDaewoo air conditioner codes

Indoor coil sensor open or short, or outdoor coil sensor open or short; unit does not work.

First step from the service manual

Check fixing of indoor coil thermistor; check indoor and outdoor coil sensors for open or short.

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

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What ON LAMP 1 blink (8s interval) means on a Daewoo air conditioner

The ON LAMP 1 blink code with an 8-second interval on a Daewoo air conditioner signals a fault detected in either the indoor coil thermistor, the outdoor coil sensor, or both. These thermistors are negative temperature coefficient (NTC) resistors that continuously report refrigerant coil temperatures to the control board. When the control board reads a resistance value outside the expected operating range, either too high (open circuit) or too low (short circuit), it classifies the sensor as faulty and shuts down unit operation entirely to prevent compressor or heat exchanger damage.

An open circuit condition occurs when the thermistor or its wiring has a break, causing resistance to read as infinite. A short circuit condition occurs when the sensor or wiring has an unintended connection to ground or another conductor, causing resistance to drop near zero. Both conditions render the sensor reading unusable. The indoor coil thermistor is physically clipped or secured directly to the evaporator coil, and a loose mounting position can cause erratic readings that the board interprets as an out-of-range fault even when the sensor itself is undamaged.

Because both the indoor and outdoor coil sensors are flagged under this single error code, diagnosis requires checking each sensor circuit individually. The first step is confirming the indoor coil thermistor is properly seated and secured to the coil. From there, each sensor should be tested for continuity and resistance. A healthy NTC thermistor will show measurable resistance that decreases as temperature rises. Any reading of zero ohms or infinite resistance confirms a failed sensor or damaged wiring harness requiring replacement.

Source: manufacturer service documentation.

Common causes of ON LAMP 1 blink (8s interval)

  1. 01

    Loose or dislodged indoor coil thermistor

    Wiring / connection

    The indoor coil thermistor is clipped directly onto the evaporator coil. If it slips out of position, the control board can receive erratic or out-of-range readings and trigger this fault. Visually inspect the clip and confirm the sensor is in firm contact with the coil.

  2. 02

    Failed indoor coil thermistor (open or short)

    Part replacement

    The thermistor itself can fail internally, resulting in either infinite resistance (open) or near-zero resistance (short). Testing the sensor with a multimeter at a known temperature will confirm whether resistance is within the expected range for a functional NTC sensor.

  3. 03

    Failed outdoor coil sensor (open or short)

    Part replacement

    The outdoor coil sensor is exposed to harsher environmental conditions and can fail due to moisture intrusion, corrosion, or physical damage. Check its resistance with a multimeter and inspect the sensor body and connector for visible damage.

  4. 04

    Damaged wiring harness or connector

    Part replacement

    Broken wires, corroded connector pins, or pinched harness sections between either sensor and the control board can create an open or short circuit reading without the sensor itself being defective. Inspect the full wiring run from each sensor back to the board.

  5. 05

    Faulty indoor control board

    Part replacement

    If both sensors test within normal resistance ranges and wiring is intact, the control board's sensor input circuit may have failed. This is less common but should be considered after all sensor and wiring checks come back normal.

See the test procedure for each cause

Frequently asked questions about ON LAMP 1 blink (8s interval)

What does ON LAMP 1 blink (8s interval) mean on a Daewoo air_conditioner?
This blink pattern indicates the control board has detected a fault in the indoor coil thermistor, the outdoor coil sensor, or both. The board is reading either an open circuit or a short circuit from one of these sensors. Because accurate coil temperature data is required for safe operation, the unit shuts down completely until the fault is resolved.
Can I fix the ON LAMP 1 blink error myself?
In some cases, yes. The first thing to check is whether the indoor coil thermistor has simply come loose from its mounting clip on the evaporator coil. Reseating it firmly costs nothing and may clear the fault. However, if a sensor has actually failed or wiring is damaged, replacement parts and basic electrical testing skills are needed, which may be beyond a typical DIY repair.
Will resetting the air conditioner clear this error code?
A power reset may temporarily clear the blink code, but if an underlying sensor fault exists, the error will return once the unit attempts to operate. The control board will re-detect the out-of-range resistance reading and shut down again. A reset is useful for confirming whether the fault is intermittent, but it is not a repair.
Is it safe to run my Daewoo AC while it shows this error?
The unit is designed to stop operating when this fault is detected, so it will not run in most cases. If it were somehow forced to run without valid coil temperature feedback, there would be risk of coil icing or compressor damage. It is best to leave the unit off and resolve the sensor fault before attempting further operation.
How much does it cost to repair the ON LAMP 1 blink error on a Daewoo air conditioner?
If the fix is simply reseating a loose thermistor, there is no parts cost and minimal labor. If a sensor requires replacement, parts typically range from a few dollars to around $30 to $60 depending on the specific sensor and availability. If the control board is at fault, costs rise significantly, generally in the range of $80 to $200 or more including labor.

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