Outdoor Board LED1 (green) blinks three times and LED2 (red) blinks five times alternately - Abnormal low pressure (Low pressure switch 63L worked)

What does U8, Ud mean?

During startup or operation, the outdoor unit's LED1 (green) blinks three times and LED2 (red) blinks five times alternately, indicating abnormal low pressure due to the low-pressure switch (63L) activating.

• Abnormal low pressure; low pressure switch (63L) activated.
• Stop valves are not open.
• Refrigerant shortage or leak.

Click steps to track your progress.

1. 1

   Check if the connector (63L) on the outdoor controller board is not disconnected.

2. 2

   Ensure all stop valves are fully open.

3. 3

   A qualified technician should inspect for refrigerant leaks and verify the refrigerant charge.

4. 4

   If the issue persists, measure resistance values of the linear expansion valve.