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.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Correct the refrigerant amount to the proper level.

2. 4

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