Daewoo Air Conditioner Error Code 1 blink (ON lamp)

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.

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.

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.

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.

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.