Samsung Air Conditioner Error Code 221

Error code 221 indicates an outdoor unit temperature sensor fault. The control board has detected that the sensor's voltage signal is either above 4.9V (corresponding to an open circuit or a reading below -50C) or below 0.4V (corresponding to a short circuit or a reading above 93C). The system treats both conditions as sensor failures and stops normal operation until the fault is resolved.

It is not advisable to continue running the unit while error code 221 is active. The system lacks valid outdoor temperature data, which can cause the control logic to make incorrect decisions about compressor operation or refrigerant flow. Operating without reliable sensor input risks compressor damage or inefficient and potentially harmful cycling.

A power reset may temporarily clear the error display, but if the underlying fault in the sensor circuit is still present, the code will return quickly once the system restarts and the control board checks the sensor signal again. A reset is useful for confirming whether a fault is intermittent, but it does not address or repair the defective wiring, connector, or sensor causing the error.

Some causes of error code 221 are accessible to a knowledgeable DIYer. Checking the outdoor sensor connector for looseness, corrosion, or moisture and reseating it requires no special tools. Testing the thermistor resistance with a multimeter is also straightforward. However, if the PCB or internal wiring harness needs replacement, a qualified HVAC technician is recommended.

Repair costs depend on the root cause. If only the connector needs cleaning or reseating, there may be little to no parts cost, with a service call fee typically ranging from $75 to $150. A replacement outdoor temperature sensor generally costs between $15 and $60 for the part. If the outdoor PCB is at fault, parts and labor combined can range from $200 to $500 or more depending on the model.