Daewoo Air Conditioner Error Code 1 blink (0.5s cycle)

The 1 blink (0.5s cycle) fault code on a Daewoo air conditioner indicates an open or short circuit condition in the outdoor coil sensor, also called the outdoor heat exchanger thermistor. This sensor is a negative temperature coefficient (NTC) thermistor that monitors the temperature of the outdoor refrigerant coil during operation. The control board uses this reading to regulate defrost cycles, prevent coil icing, and protect the compressor from operating under extreme coil temperature conditions. When the sensor signal falls outside the expected resistance range, the board logs this fault and triggers the blink pattern.

A key characteristic of this fault code is that the unit continues operating despite the sensor fault. This means the system has not shut down, but is running without accurate outdoor coil temperature feedback. While convenient in the short term, operating without this input can reduce efficiency, cause the system to miss defrost cycles, or allow the coil to operate outside safe temperature boundaries over time. The fault should be addressed promptly even though it is not immediately disabling.

The most common root causes include a disconnected or corroded connector at the sensor harness, a failed thermistor that has drifted out of range, or damaged wiring along the sensor lead. The first diagnostic step is to inspect the outdoor coil sensor connections for loose pins, corrosion, or moisture intrusion. If connections are intact, the sensor itself should be tested with a multimeter to verify its resistance matches the expected value for the ambient temperature at the time of testing.