Is the summer heat making you super sweaty and your Daikin AC refuses to cool things down? When your Daikin AC flashes a U4 code, it indicates a communication problem between the appliance’s units. This lack of communication prevents you from the cool air you are grasping for. While Daikin is a high-rated brand, this error can occur due to wiring problems, loose connections, or faulty control boards. The good news? You might be able to investigate this issue and fix it yourself.
But before we dive deep into the causes and fixes of your Daikin U4 error code, let’s explore the commonly affected models by this problem:
- Daikin FTXS25K5
- Daikin FTXS35K5
- Daikin FTKZ50LTXS
- Daikin FTYN25PX
- Dakin Skyair FTXS-T
- Dakin Skyair FTYN-L
- Dakin Sensira FTXA
- Dakin Sensira FTXS-KB
- Dakin Aurora FTXA-LB
- Dakin Aurora FTXS-JV
- Dakin Perfera FTXA-BQ
- Dakin Perfera FTXS-KF
What Does U4 Mean On A Daikin AC?
- Meaning: When your Dakin AC blinks U4, it expresses miscommunication between the indoor and outdoor units.
- Safety Feature: This communication fault is more than a blinking code. It is a built-in safety mechanism. Any miscommunication between the outdoor and indoor units can cause complex issues but the error message halts the AC’s operation to avoid further problems.
- Impact on Use: Your AC won’t produce cool air, leaving you feeling hot, uncomfortable, and frustrated.
- Warning Signs: Besides the code, your AC might show inconsistent lights or an unresponsive system. Also, you may notice the lack of cool air circulation.
- Importance of Addressing: Ignoring U4 can lead to system inefficiency or costly damages. It’s crucial to address the communication issue to restore cool air function and prevent potential damage to your AC system.
Why Does Your Daikin AC Throw U4 Error?
When your Daikin air conditioner displays a U4 code, it sends a cry for help. It needs immediate interference to solve the communication error and restore its functionality. Let’s explore the common causes behind this Daikin error code:
1. Power Supply Issues
Both indoor and outdoor units rely on a steady power supply to function. Various components like the fan motor, compressor, and circuit boards (indoor PCB) need consistent power to operate correctly.
Repeated fluctuations or outages in power can disrupt the communication signal between the units, triggering the U4 error. The disruption of the power supply is associated with your home’s electrical system, temporary grid issues, or even blown fuses within the AC unit itself.
2. Communication Disruption
This problem stems from loose wires. Your AC system considers its wiring system a lifeline of communication. Internal wiring transmits data for proper operation. Wires connected to sensors like thermistors can also lead to similar issues.
Loose or damaged connections within these wires can disrupt the signal, causing a communication breakdown and a Daikin U4 error. This could be due to normal wear and tear, improper installation, or vibration during operation.
3. Faulty Circuit Board (PCB)
Both the indoor and outdoor units have a PCB. The PCB acts as the brain of each unit, processing signals and controlling various components. A malfunctioning PCB in either the indoor or outdoor unit could disrupt the communication protocol, leading to your Daikin U4 error. This could be caused by a component failure on the board, power surges, or overheating.
4. Communication Cable Malfunctions
This communication cable is dedicated to transmitting data between the indoor and outdoor units. This cable is essential for proper communication between the circuit boards “brains” of each unit.
Damage to this cable occurs due to cuts, corrosion, or faulty connections. These issues can disrupt the communication signal, resulting in the Daikin U4 error.
Besides natural wear and tear, improper handling during maintenance may cause communication cable malfunctions.
How To Reset Daikin AC U4 Error
Resetting your Daikin AC can clear the U4 error by rebooting the system’s control logic, and resolving temporary communication glitches or rare software problems.
Here’s how to reset your Daikin AC U4 error:
- Turn off the AC with the remote controller or the indoor unit button. Wait between 3 and 4 minutes, then restart.
- Turn on the AC to check if the code has disappeared.
- Check your user manual to see if your Daikin AC has a reset feature on the remote. If it has a dedicated “reset” button on the remote, press it according to the manual’s instructions. This could be another way of resetting your AC error code.
How To Fix Daikin AC U4 Error
In many cases, the malfunctioning components leading to the Daikin U4 error need the intervention of a professional technician. But before contacting a pro for complex repairs, you can try a few DIY fixes and simple troubleshooting procedures.
1. How To Fix Power Supply Issues
Ensure that both the indoor and outdoor units are securely connected to their designated electrical outlets or breaker switches. Look for tripped circuit breakers or blown fuses in your home’s electrical panel.
Reset the breaker if tripped, but if a fuse is blown, replacing it yourself might be risky. Consult an electrician if unsure.
2. How To Fix Communication Disruption
To fix this problem, you will need access to the indoor unit’s wiring harnesses. To have this access, you should remove the unit’s front access panel. Use a flathead screwdriver to open the panel. Focus on the visible portions of the wiring for loose connections, damage, or corrosion.
Look for loose wire nuts or terminals. tighten any loose wire nuts by turning them clockwise with your screwdriver. As for loose terminals, you should tighten the screw holding the wire in place with your screwdriver.
3. How To Fix Faulty Circuit Board (PCB)
The circuit boards of both units have a complex nature. So, it is recommended to avoid DIY repair attempts unless you have sufficient knowledge. You can find the PCB behind the removable panel. Both boards look identical. So, once you remove the panels, you should look for a flat board with electronic components mounted on it,
In most cases, problems with the control board require replacing the delicate component. But a repair technician might find the source of the issue and might find a replacement solution. You can identify a faulty board from its appearance. It might have corroded wires or burnt components.
If you have advanced electrical knowledge and practice, you can use a multimeter to test for continuity.
4. How To Fix Communication Cable Malfunctions
Addressing the communication cable is similar to the wiring harness issues. To correctly work on this component, you should Find the cable that connects the indoor and outdoor units. This cable runs between the indoor and outdoor units, often alongside the refrigerant lines.
Now bring your screwdriver and do the following:
- Start by removing the indoor unit’s panel.
- Look for a bundled cable that connects to the PCB and runs towards the outdoor unit.
- If the cable shows obvious physical damage, including frayed, or corroded wires, opt for a replacement cable. However, it’s better to get a professional Daikin technician to replace it for you.
Remember: Any of these troubleshooting steps should be done with the AC turned off and the circuit breaker is on the off position.
Conclusion
Now that you’ve reached the end of this troubleshooting guide, you have explored many necessary details about the Daikin U4 error code. It means your cool comfort is on hold due to a communication glitch between the indoor and outdoor units. While frustrating, the U4 code is a safety feature preventing further issues.
Power supply issues, communication disruption, faulty circuit boards, and communication cable malfunctions are common causes. Try troubleshooting steps like checking power connections, inspecting wiring, or seeking professional assistance for complex repairs.
Don’t let the U4 error code keep you hot and bothered—take control of your comfort today!
Adrian is an ISCET licensed professional that has completed the National Appliance Service Technician Certification Exam and has the expertise to diagnose and repair any appliance. He is well-versed in the latest technologies and techniques and is always up-to-date on the latest industry standards.
