Abnormal Low Pressure (63L Activated)

What does UL (100) mean?

The low-pressure switch (63L) is activated, detecting pressure under -0.01MPa [-1.5PSIG] during compressor operation. This indicates either a closed stop valve on the outdoor unit, disconnection or loose connection of the 63L connector or the 63L switch itself, a defective outdoor controller board, refrigerant leakage or shortage, or a malfunction of the linear expansion valve.

• System pressure dropped below the set limit (63L activated).
• Refrigerant leak in the system.
• Low refrigerant charge.
• Clogged indoor unit filter or evaporator.
• Malfunctioning expansion valve.

Click steps to track your progress.

1. 1

   Check the stop valve of the outdoor unit to ensure it is open.

2. 2

   Turn the power off and on again to check if F1 is displayed. If F1 is displayed, follow the F1 processing direction (further details not provided in this manual excerpt).

3. 3

   Correct the refrigerant amount to the proper level.

4. 4

   Check the linear expansion valve. Refer to section 10-6.