Daewoo Air Conditioner Error Code ON LAMP Blink (continuous)

A continuous blinking ON lamp on a Daewoo air conditioner indicates the control board has detected an open or short circuit condition in the room temperature thermistor. The thermistor is the sensor that measures ambient room temperature inside the indoor unit. The unit continues to operate in a failsafe mode with the room temperature fixed at 32 degrees Celsius, but accurate temperature control is lost until the fault is resolved.

The unit will continue operating in failsafe mode, but it is not running correctly. Because the room temperature is fixed at 32 degrees Celsius internally, the compressor will run continuously without proper cycling. Extended operation in this condition can increase wear on the compressor and raise energy consumption, so the fault should be addressed promptly.

If only the thermistor needs replacement, parts and labor typically range from $50 to $150 depending on the specific unit model and local labor rates. If the control board requires replacement, costs can range from $150 to $400 or more. Getting a diagnostic visit from a qualified technician first will help confirm exactly which component needs to be replaced before committing to a repair.

A knowledgeable DIYer comfortable with basic electrical testing can diagnose this fault by measuring the thermistor resistance with a multimeter. If the thermistor reads open or shorted, replacing it is a relatively straightforward repair. However, if the wiring harness or control board is involved, professional diagnosis is recommended to avoid further damage.

A power reset will not permanently clear this fault because the condition is caused by a hardware problem in the thermistor circuit. The fault will return as soon as the control board re-checks the sensor after restart. The underlying issue with the thermistor, wiring, or connector must be repaired before the fault code will clear and stay clear.