Common Daikin Air Conditioner Fault Codes and How to Troubleshoot Them

Key Takeaways

• Knowing the different Daikin air conditioner fault codes can help you quickly identify specific issues within your unit. 
• Common codes like U4, A1, L5, C4, and E5 indicate problems ranging from wiring issues to inverter faults.
• Some issues can be resolved through basic checks, but complex faults require professional help.

Decoding Daikin: What Those Fault Codes Really Mean

Seeing a strange number or letter flashing on your Daikin aircon display? Don’t panic—these fault codes are your Daikin air conditioner unit’s way of telling you that something isn’t working as it should. From minor sensor errors to serious electrical faults, each code gives valuable insight into the system’s condition.

In this guide, we’ll cover some of the most common fault codes and share practical Daikin troubleshooting tips you can try before calling a technician. Knowing what these codes mean helps you respond quickly, prevent further damage, and keep your home cool and comfortable.

1. U4: Communication Error Between Indoor and Outdoor Units

The U4 fault code often appears when there’s a communication breakdown between the indoor and outdoor units. This could stem from wiring issues, loose connections, or a temporary power disruption.

How to troubleshoot:

• Turn off your aircon for a few minutes, then restart it.
• Inspect visible wiring for signs of looseness or damage.
• Ensure all power connections are secure.

If the code persists, it could point to a more serious problem within the control circuit board. In such cases, it’s best to seek professional Daikin aircon troubleshooting and repair services to identify the root cause and prevent electrical damage.

2. A1: Indoor PCB Fault

The A1 error signifies a problem with the indoor unit’s printed circuit board (PCB), also known as the “brain” of your air conditioner. A power surge or electrical short could be the cause.

How to troubleshoot:

• Switch off the power for about five minutes to reset the system.
• If the fault reappears, avoid prolonged use. Continuing to run the unit could worsen the damage.

This issue often requires a thorough inspection or replacement of the affected PCB components by a qualified technician to ensure safe operation and prevent further electrical faults.

3. L5: Inverter Instantaneous Overcurrent (DC)

This Daikin air conditioner fault code appears when the inverter detects an excessive surge of direct current. This may occur due to a faulty compressor, damaged wiring, or power fluctuations.

How to troubleshoot:

• Turn off the power supply immediately to prevent further electrical damage.
• Check your home’s power stability or circuit breaker.
• Avoid attempting DIY electrical work, as this type of fault usually requires a technician to test and replace parts safely.

If left unresolved, this issue could result in your AC not working at all, disrupting your comfort and potentially damaging key components.

4. C4: Malfunction of Liquid Pipe Thermistor for Heat Exchanger

If your Daikin unit displays a C4 error, the issue lies in the thermistor (temperature sensor) that monitors the heat exchanger. When faulty, it can cause inaccurate temperature readings or inconsistent cooling.

How to troubleshoot:

• Ensure the air filters and coils are clean and free of debris.
• Restart the system after a few minutes of power down.
• If cooling remains irregular, the thermistor may need to be replaced.

5. E5: Inverter Compressor Motor Malfunction or Overheating

The E5 error is among the most serious Daikin air conditioner fault codes. It often means the inverter compressor motor has overheated or is malfunctioning. Possible causes include blocked coils, poor ventilation, or worn electrical components.

How to troubleshoot:

• Switch off your aircon immediately to let it cool down.
• Clean the outdoor unit area to improve airflow.
• Resume operation and monitor for recurrence.

If the code reappears, it’s best to contact professional aircon repair services to inspect the compressor and prevent long-term damage.

Need Help with a Fault? Cool Channels Engineering Has You Covered

Understanding the meanings of these common aircon fault codes allows you to react quickly and make informed decisions before small issues escalate. While basic troubleshooting can resolve minor glitches, persistent or complex errors, especially those involving electrical components, require expert attention.

At Cool Channels Engineering, we offer professional aircon troubleshooting and repair services for various brands, including Daikin, Mitsubishi, Panasonic, and Samsung. Our trained technicians can accurately diagnose issues, replace faulty components, and restore your system’s efficiency. 

Seeing a fault code on your Daikin air conditioner? Don’t wait for the issue to get worse. Contact us for fast, reliable diagnostics and repairs today.