Troubleshoot error code “P3” in Ferroli air-conditioning

How to eliminate P3 error in Ferroli air conditioning?

  • Error: P3
  • Description: Compressor current protection – Compressor protection against overcurrent
  • Cause: Anomalous power supply, poor heat exchange in the evaporator, blockage in the high-pressure zone, damaged inverter module, damaged compressor, and damage to the main circuit board.
  • Solution: Verify that the power supply voltage adheres to the specified limits.


Compressor intensity protection is a safety mechanism built into refrigeration systems. When the compressor intensity exceeds specific protection values for each model (18 A in single-phase models of 4/6 kW, 20 A in the single-phase model of 8 kW, 31 A in single-phase models of 10-16 kW, 15 A in three-phase models), the system enters a protection state, displaying error code “P3,” and the control device, such as M-Thermal Split, automatically stops. Once the compressor intensity returns to normal levels, the error code is cleared, and the refrigeration system resumes normal operation.

Possible Causes

Compressor intensity protection can be triggered by several reasons:

  • Anomalous Power Supply: Variations in the electrical power supply can lead to a sudden increase in compressor intensity, triggering the protection mechanism.
  • Poor Heat Exchange in the Evaporator: If the evaporator is not efficiently exchanging heat, the compressor has to work harder to maintain the desired temperature, which can lead to increased intensity and activate the protection.
  • High-Pressure Zone Blockage: Obstruction in the high-pressure zone of the system can cause an increase in pressure and subsequently in compressor intensity.
  • Damaged Inverter Module: Modern refrigeration systems often incorporate inverter modules to control compressor speed. If this module is damaged, it could cause fluctuations in intensity.
  • Damaged Compressor: A faulty or damaged compressor can operate incorrectly, resulting in unusually high intensity.
  • Main Circuit Board Damage: The main circuit board that controls system operation may sustain damage due to various factors, affecting the control of compressor intensity.

Solution: Addressing Compressor Intensity Protection

Dealing with the issue of compressor intensity protection requires a systematic and precise approach. Below are some possible solutions to address this problem:

1. Power Supply Verification

Start by inspecting the electrical power supply that feeds the refrigeration system. Ensure there are no significant voltage and current fluctuations. If necessary, consider installing voltage regulators or surge protection systems to ensure a stable power supply.

2. Evaporator Maintenance

Regularly perform maintenance on the evaporator to ensure it is clean and in good condition. Optimal heat exchange will reduce the load on the compressor and decrease the likelihood of activating protection due to high intensity.

3. High-Pressure Zone Inspection

Thoroughly examine the high-pressure zone of the refrigeration system to detect possible obstructions or blockages. Clear any accumulated dirt or debris that might be affecting refrigerant flow.

4. Inverter Module Evaluation

If the refrigeration system uses an inverter module to control compressor speed, make sure it is functioning correctly. If it is suspected to be damaged, replace it with a new, high-quality unit and ensure proper installation.

5. Compressor Inspection

If the above solutions do not resolve the issue, you may need to inspect the compressor for possible damage or malfunction. If a faulty compressor is confirmed, replace the unit with a compatible, high-quality model.

6. Main Circuit Board Assessment

Finally, if all other solutions fail to resolve the problem, examine the main circuit board. Look for visible signs of damage, such as burns, detached components, or broken traces. If the board is damaged, replace the unit or repair the faulty components.

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