UL - Abnormal low pressure in outdoor unit

What does UL mean?

This code indicates that the system has detected abnormally low pressure within the outdoor unit, often due to a lack of refrigerant.

• Refrigerant leak in the system.
• Insufficient refrigerant charge.
• Faulty low-pressure sensor.
• Clogged filter drier or restricted refrigerant flow.

Click steps to track your progress.

1. 1

   Turn off the air conditioning system at the main power switch.

2. 2

   Check the outdoor unit for any visible signs of ice formation on the refrigerant lines, which can indicate low pressure.

3. 3

   Contact a qualified HVAC technician to diagnose the low pressure, check for leaks, and recharge the system.

4. 4

   Do not operate the unit with low refrigerant, as it can cause further damage.