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

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

What this means:
This error occurs when either:

• The high pressure exceeds 4.4 MPa, or

• The low pressure drops below 0.13 MPa.
  These readings are detected by the system’s pressure switches, and the unit will shut down to prevent compressor damage.

Try this first (quick reset):

1. Turn off power to the unit.

2. Wait 2 minutes.

3. Turn it back on and check the display.

• If the error clears — monitor the system for recurrence.

• If it returns — proceed with the detailed diagnosis below.

Next steps (for technicians):

High Pressure Side:

1. Check wiring between high pressure switch and control board:

   • If not wired correctly → correct it.

   • If yes → unplug and measure resistance.

2. Measure resistance of high pressure protector:

   • If resistance ≠ 0 → replace the high pressure protector.

   • If normal → continue.

3. Is outdoor temperature > 50°C?

   • Yes → allow the unit to cool down.

4. Check outdoor ventilation and heat exchanger:

   • If poor airflow or dirty coil → improve ventilation and clean the heat exchanger.

   • Ensure outdoor fan is working. If not → replace it.

5. If none of the above fix the issue:

   • Replace the outdoor main PCB.

Low Pressure Side:

1. Check wiring between low pressure switch and PCB:

   • If not wired properly → fix it.

2. Measure resistance of low pressure protector:

   • If resistance ≠ 0 → replace the low pressure switch.

3. Is outdoor temperature too low?

   • Yes → unit may be in protection due to ambient conditions.

4. Check refrigerant system:

   • If refrigerant level is low → add refrigerant.

   • If system works normally after charging → continue operation.

   • If not → inspect further for leaks or restrictions.

5. Check indoor fan operation (cooling mode):

   • If fan isn’t running → resolve fan malfunction.

6. If all checks are OK but error remains:

   • Replace the outdoor main PCB.

What you might need:

• High and low pressure switches

• Connection wires

• Outdoor fan

• Outdoor main PCB

• Additional refrigerant

• Leak detection tools

Helpful tip:
Fan malfunction, dirty coils, and insufficient refrigerant are common causes of PC 03. Always verify airflow and refrigerant status before swapping components.

Click here to view the detailed guide.TS29