Daikin Mini Split Error Codes (Troubleshooting Guide)

When it comes to choosing the best mini-split brands on the market, Daikin is usually at the top of the list. They offer many high-quality heating and cooling products, and mini-split heat pump systems are one. Like all mini-splits, however, many problems can happen with those made by Daikin. 

Because problems are inevitable with mini-splits, Daikin has an error code and troubleshooting guide that they equip with each of their units. You’ll notice a green light flashing on the front of the unit, indicating there’s a problem. Next, you use your remote control to determine the error code and look it up in your owner’s manual for further instruction. 

You would not need error codes and troubleshooting guides in an ideal world. Although Daikin mini-splits are some of the best on the market, they’re electrical appliances and are prone to issues. In this article, we’ll look at some of the most common issues and error codes and what to do about them. 

How to Find the Fault Code on a Daikin Mini Split 

Daikin has a slightly different fault code system than many mini split brands. Mitsubishi, Pioneer, and others have the error code pop up on the surface of the head unit with flashing white lights. Daikin, however, has a light above the power button that flashes green when there’s an error. Here’s what you need to do. 

  1. Once you see the flashing green light, you know there’s a problem. 
  2. Retrieve your remote control and press the CANCEL button for six seconds. 
  3. After six seconds, you should see a double zero, 00, show up on the display. 
  4. Once you see the double zero, press the CANCEL button once more. 
  5. Pressing the CANCEL button will pull up a list of error codes. 
  6. Every time you press the CANCEL button, you should hear a quick beep. 
  7. Once you reach the error code causing your mini-split to malfunction, you’ll hear a long beep. 
  8. The error code beep will be noticeably different than the rest of the beeps. 

Once you find the correct error code, you will have to look it up in your owner’s manual or on Daikin’s website. These resources will explain what the error code means, possible causes, and how to troubleshoot it. 

Common Problems That Will Cause an Error Code

Error codes don’t just happen by accident. There’s always an underlying problem that causes the issue in the first place. The only way to get your mini-split working again is to fix the root of the problem. Otherwise, the error code will persist. 

Dirty Air Filters 

The air filters on your mini-split are inside the head unit, just below the outer cover. Your air filter’s job is to trap dirt, debris, and particles as your mini-split sucks air in and then pushes it back out. However, the filters can only handle so much dirt before it starts to pile up and block air flow. Numerous error codes get tripped because of a dirty air filter. 

Clogged Drain Line 

Aside from air filters, a clogged drain line is the second-most common cause for error codes. The drain line is behind your indoor unit, and its job is to carry condensation that accumulates inside the head unit out of your home. If this line gets clogged or damaged, one or more error codes will pop up. 

Wiring Problems 

Two different wires get wired into your mini-split system. The first is an electrical wire from your main panel box to your outdoor unit. The second is a communication wire that connects your indoor unit to your outdoor one. If anything happens with either of these two wires, error codes could occur. 

Frozen Evaporator Coils 

Frozen evaporator coils can occur on your inside unit or your outside unit. While they will trip an error code, they’re almost always the result of an underlying problem. Dirty air filters, refrigerant problems, thermistor issues, and many other things can cause your evaporator coils to freeze up. 

Luckily, your mini-split is equipped with an auto-defrost system that turns the mini-split off and defrosts the coils when this happens. While this will keep the problem at bay and prevent further damage, your coils will continue to ice over until you get to the root of the problem. 

Refrigerant Issues

You can have too much or too little refrigerant, which will cause problems. The only way to check your refrigeration levels is to contact a heating and cooling pro with the proper equipment and training. 

Common Fault Codes and How to Fix Them

Fault Code U0 – Low Refrigerant 

If you have a U0 error code pop up on your remote, your system is low on refrigerant. Your system needs refrigeration for both the heating and cooling sides of the mini-split operation. If it’s low on refrigerant, there’s a very good chance that your coils will either get too cold or too hot, depending on whether you’re using your unit for heating or cooling. 

A mini-split can operate for a long while with minimally low refrigerant, but the unit will shut down if the levels get too low. 

What to Do

The only way to fix the problem of low refrigeration is to add more refrigerant to the unit. Refrigeration checks can only be done by a seasoned HVAC pro with the right tools. However, it’s important to figure out why your refrigerant was low in the first place. Otherwise, the problem will persist. 

Unless the distance between your indoor unit and your outdoor one is more than 50′, the cause of low refrigeration is because you have a leak. Leaks can occur on your outdoor or indoor evaporator coils or refrigeration lines. Unless you fix the leak, your HVAC system will keep losing refrigerant, and your evaporator coils will continue to freeze or overheat. 

Fault Code A3 – Drain Level Abnormality 

If you have an A3 error code, you have a problem with your condensate drain. The most likely reason is that your drain line is kinked or clogged by something. Drain lines are finicky to install, even for seasoned professionals. Because of where the drain lines are on mini-splits and how the head units get installed, they can kink during installation. 

It’s also possible for dirt, debris, or even a small animal to get into the interior or exterior portion of the pipe and clog it up. Your mini-split can recognize this problem and set off an error code, hopefully before water piles up and spills out into your indoor living space. 

What to Do 

Fixing a clogged drain line will either be very easy or difficult, depending on where the problem lies. Here’s what you need to do. 

  1. Turn off power to the unit. 
  2. Remove the head unit of your mini-split from the mounting bracket. 
  3. Purchase or rent a head unit holding bracket to support the unit, so your hands are free to work on the drain line. 
  4. Detach the drain line from the back of the unit and inspect it for clogs or kinks. 
  5. Lift the front cover to access the condensation reservoir and check for a blockage. 
  6. Pour water into the detached portion of the drain line and have someone standing outside where the drain terminates. If water passes through the drain, your problem lies within the head unit. 

While clogs and kinks are the most common reason for an A3 error code, there are other possibilities. You could also have a defective drain pump, float switch, or short circuit connector. Unless you have electrical experience, it would be best to contact a mini-split service tech and have them diagnose the problem. 

Fault Code A6 – Broken Fan Motor 

An A6 fault code means there’s a problem with the fan on the head unit. Your fan’s job is to suck air back into the head unit, which then gets heated up or cooled down. Once it’s the appropriate temperature, your fan blows the air through the front vents and into your home. If the fan motor is bad or broken, air will get sucked into the inside unit, get extremely hot or cold, but won’t be able to leave the unit. 

The result is that your evaporator coils will either overheat or ice over. 

What to Do

The first thing you want to do is determine if your fan isn’t working. To do this, turn your mini-split on and allow it to start operations. Put your hand in front of the air vents and feel for air exiting the vents. If your mini-split is running, but you feel little to no air, your fan is likely busted, especially if an A6 error code accompanies the problem. 

Unfortunately, all of the possible causes for a broken or defective fan motor are electrical. You’ll need a multimeter and adequate electrical training to diagnose the problem. It could be something as simple as a loose or frayed wire, but it could also be that you need to replace your fan motor. It could also be a problem with the circuit board. 

Fault Code A5 – Evaporator Coils Overheating or Frozen 

As we discussed above, a frozen or overheated evaporator coil could get caused by many things. However, you’ll see an A5 error code pop up on your remote control when this happens. 

What to Do

To fix an A5 error code, you have to figure out why your coils are freezing up or overheating. 

  1. Check the air filters in the indoor unit and clean them if they’re dirty. 
  2. Check to make sure the fan is working in the indoor unit. 
  3. Ensure no debris is blocking the airflow around the outdoor unit and that nothing inhibits the fan from spinning. 
  4. If none of these cause your issue, you likely have low refrigerant. 
  5. Contact a heating and cooling specialist to check your refrigerant levels and refill them if necessary. 

Fault Code U4 – Communication Error Between Indoor and Outdoor Units 

A U4 fault code is a communication error and usually results from improper wiring on the indoor and outdoor units. There’s a black, round communication wire connecting the indoor unit to the outdoor one. This wire has four smaller wires inside it that attach to four different leads on either unit. 

It’s vital that the different colored wires are attached in the same order inside and outside and that they’re secure. Otherwise, you’ll have a communication error and a U4 error code. 

What to Do

  1. Remove the protective cover on the outdoor condenser and locate where the communication wires are attached. 
  2. Lift the outer cover on the indoor unit and remove a second cover on the bottom right of the unit to access the communication wires. 
  3. Ensure that the wires are connected in the same order on the inside and outside units. 
  4. Ensure that the wires are securely snug but not overtightened. Wires that are too tight or too loose will malfunction, and you’ll have a communication error. 
  5. If everything checks out, the wire is likely severed or pinched somewhere between the two units. 

How to Reset a Daikin Mini-Split 

If you see an error code on your Daikin mini-split outside of the ones listed above, there’s a chance that you can fix it by resetting the unit. Resetting a mini-split is like resetting your phone or laptop. Many glitches and hiccups resolve themselves when the system resets and restarts. 

To do that with a Daikin mini-split, here’s what you need to do. 

  1. Turn off the mini-split system.  
  2. Locate your main panel box inside your home. 
  3. Find the circuit breaker that controls your mini-split. 
  4. Turn the circuit breaker to the OFF position. 
  5. Wait for a minute or two, then turn the breaker back to ON. 
  6. This simple action is a system reset for your Daikin mini-split and will resolve many issues. 
  7. Turn your mini-split system on and see if the error code resumes. 
  8. If it does, find out which error code it is and what it means, and resolve it accordingly. 

Related Questions 

Why is my Daikin mini-split blinking an orange light? 

A flashing orange light on your mini-split means that the Streamer unit needs cleaning. Turn off the system, clean the Streamer unit, and restart the system, and the orange light should be gone. 

Why does my Daikin mini-split keep turning off? 

Once your mini-split reaches the set temperature, it will automatically turn off or enter Breeze mode. If, however, your mini-split stops running and you notice the green light is on, it means that you have an error code that needs to get resolved before it will start running again. 

How do you troubleshoot a Daikin mini-split? 

The only way to troubleshoot your Daikin mini-split is to figure out which error code is causing the problem and fix it. You can fix some problems yourself, but others will require the help of a professional. 

Final Thoughts 

When it comes to mini-splits, Daikin is one of the best brands. While they’re more reliable than most, Daikin’s aren’t immune to problems, and you should still expect your fair share of them. By taking care of your mini-split and having it professionally maintained, you can prevent most problems from ever happening. However, you must know how to track down the right error code and resolve it when they do happen. 

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.
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