Error Code: PC 03 – Pressure Protection (Low or High Pressure)

Error Code: PC 03 – Pressure Protection (Low or High Pressure)
Applies to LETO and AURA Series (select models)

What this means:
The system has triggered a pressure protection fault due to either excessively high pressure (>4.4 MPa) or low pressure (<0.13 MPa) in the refrigerant line. This usually points to poor ventilation, system blockage, fan failure, or incorrect refrigerant levels.

Try this first (quick reset):

1. Turn off the unit completely.

2. Wait 2 full minutes.

3. Turn it back on and check if the error clears.

• If the error goes away — it may have been a temporary condition.

• If the error returns — continue with the checks below.

Next steps (for technicians):

? High Pressure Protection:

• Confirm that the high-pressure switch is properly connected to the outdoor PCB.

• Disconnect the plug and measure resistance of the high-pressure switch:

  • If resistance ≠ 0 → replace the switch.

• Check outdoor ventilation and airflow:

  • Make sure the fan is working, vents are not blocked, and heat exchanger is clean.

• If ambient temperature is high (above 50°C), ensure cooling airflow is unobstructed.

• If all above are fine, replace the outdoor PCB.

? Low Pressure Protection:

• Verify low-pressure switch wiring to the outdoor PCB.

• Test the low-pressure switch resistance:

  • If resistance ≠ 0 → replace the switch.

• Check if the outdoor temperature is too low or if the valves are fully open.

• Make sure the indoor fan is running properly during cooling.

• If refrigerant is low, recharge and observe system performance.

• If the issue persists, replace the outdoor PCB.

What you might need:

• High or low pressure switch

• Outdoor PCB

• Refrigerant

• Outdoor fan

• Connection wires

Helpful tip:
This protection is critical for compressor safety. Both high and low pressure errors can result from improper refrigerant charge, airflow restrictions, or wiring faults. Always resolve airflow issues before replacing components.

Click here to view the detailed guide.TS26-INV