Outdoor Board LED1 (green) blinks three times and LED2 (red) blinks two times alternately - Abnormality of shell thermostat and discharging temperature (TH4)

What does U2 mean?

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks two times alternately, indicating an abnormality of the shell thermostat and/or discharge temperature sensor (TH4).

• Abnormality of shell thermostat and discharging temperature (TH4).
• Connectors (TH4, LEV-A, and LEV-B) on outdoor controller board are disconnected.
• Insufficient refrigerant in the unit.

Click steps to track your progress.

1. 1

   Check if connectors (TH4, LEV-A, and LEV-B) on the outdoor controller board are not disconnected.

2. 2

   Measure resistance values among terminals on indoor valve and outdoor linear expansion valve using a tester.

3. 3

   Check if the unit is filled with the specified amount of refrigerant.

4. 4

   Ensure the shell thermostat is properly seated and functioning.