Mitsubishi mini split air conditioners arguably have some of the most premium specs on the market and are among the most reliable. But even so, these air cons can fail; thus, the need for Mitsubishi mini split troubleshooting awareness.
Knowing how to troubleshoot a Mitsubishi mini split that won’t turn on, stay on, heat up, blow air or turn off, or an option whose remote control is not working is essential. You may also need to know how to troubleshoot a mini split that’s noisy, smelly, indicating, or displaying an error code.
On that note, we’ll go through all those issues to enable you to know how to do the troubleshooting DIY. So, before you can call a Mitsubishi AC technician, you may want to try out this troubleshooting guide.
After all, a successful DIY troubleshooting means you get to save time and money. Let’s jump into it:
In a rush? See below the quick fixes to the commonest Mitsubishi mini split air conditioner problems:
Quick Mitsubishi Mini Split Troubleshooting Guide
| – | Problem | Most Probable Causes | Recommended Fix |
| 1. | Mini Split Won’t Turn On | Tripped breaker, faulty wall socket, power cord, remote or thermostat, or a refrigerant leak | Reset a tripped power breaker and replace the wall socket or power if they fail to show continuity. Also, replace the remote control’s batteries if they are dead and leave the rest to an HVAC expert |
| 2. | Mini Split Won’t Stay On | Unit under-sizing, dirty filter or coils, frozen evaporator, a faulty thermostat, or low refrigerant | Upgrade the AC if it’s too small, clean dirty coils, and replace dirty filters. Adjust the thermostat correctly and call an expert to fix a refrigerant leak |
| 3. | Mini Split Won’t Heat Up | Wrong temperature setting, dirty filter, or unit under-sizing | Set the thermostat on Auto/Heat mode and replace the dirty filter. If the unit is smaller for the space, upgrade it |
| 4. | Mini Split Won’t Blow Cold Air | Clogged filter or condenser, frozen coils, filthy outdoor unit, or low refrigerant | Clean a dirty filter or condenser and declutter the filthy outdoors. Adjust the temperature to unfreeze the coils and call an expert to fix the refrigerant leakage |
| 5. | Mini Split Won’t Turn Off | Faulty wiring or low refrigerant | Call an HVAC technician |
| 6. | Remote Control Not Working | Out of range, exhausted batteries, or batteries incorrectly installed | Move the remote close to the AC. Replace the batteries if they are dead and install them correctly |
Common Mitsubishi Mini Split Common Problems for Troubleshooting
Now, as far as Mitsubishi mini split air conditioner problems go, here are the commonest:
1. Mitsubishi Mini Split Not Turning On
Several issues could explain why your mini split AC won’t turn on. They include a tripped breaker, faulty wall socket, power cord or thermostat, a non-responsive remote, or low refrigerant.
Let’s discuss them next.
- Tripped breaker – The breaker typically trips off during a power overload and prevents the mini split from turning on.
- Faulty wall socket – A defective wall socket won’t allow current to get to your air conditioner. As a result, the AC won’t start. So, test its continuity level with a multimeter.
- Faulty power cord – If the AC’s power cord is damaged or defective, the AC won’t receive any power to turn on. So, again, use the multimeter to test the cable.
- Non-responsive remote – If the remote is not working, perhaps due to batteries, the AC won’t turn on when you press the power button. Thus, the remote control is worth checking.
- Bad thermostat – A malfunctioning thermostat can also prevent a Mitsubishi mini split from starting, and if it does start, it’ll not stay on for long. Overall, this is something an HVAC expert should fix.
- Low refrigerant – The refrigerant’s job is to absorb the heat released during the cooling process. Damage to the AC or poor installation could lead to its leakage, and once that happens, the AC may not start.
Fix
Start by resetting the circuit breaker if it is tripped. If it’s not, test the power cord and wall socket for continuity and replace the one that doesn’t show continuity. But if the problem is a bad thermostat or low refrigerant, call an HVAC expert to help you fix them.
2. Mitsubishi Mini Split Won’t Stay On
Issues such as a small AC (under-sizing), dirty filter or coils, a frozen evaporator, a defective thermostat, or a refrigerant leak can prevent a mini split from staying on. So, while the AC may turn on, it goes off soon.
Here’s what to know about the issues:
- AC under-sizing – If the mini split is smaller than the space, the AC may turn on briefly and go off. That’s why you should get an AC that matches your area.
- Dirty filter or coils – For the AC to run smoothly, there must be adequate airflow. That’s, however, not possible if the air filter or evaporator/condenser coils are dirty.
- Frozen evaporator – The evaporator may also prevent the AC from staying on longer if its ice is frozen. That’s likely due to refrigerant leakage or a very low-temperature setting.
- Defective thermostat – A faulty thermostat cannot maintain a specific temperature, making it harder for the mini split to stay on. But since it’s hard to diagnose, leave it to an HVAC expert.
- Refrigerant leak – A low refrigerant level due to leakage could also make it hard for the AC to stay on. For that reason, you should talk to an HVAC expert right away.
Fix
Ensure your AC matches your space. If not, upgrade it. Check the coils and air filter and clean them if dirty. You can replace the air filter instead. Adjust the temperature to prevent a frozen evaporator and leave the other issues to an HVAC expert.
3. Mitsubishi Mini Split Not Heating (Not Blowing Hot Air)
Issues such as a low-temperature setting, dirty filter, or a unit under-sizing (smaller AC) can prevent a mini split from blowing hot air. Here’s what to know:
- Low-temperature setting – If the thermostat’s temperature is lower than the room temperature, the AC won’t blow hot air. So, check and adjust the unit’s temperature setting accordingly.
- Dirty filter – Dirt clogs the air filter and interferes with airflow. In the end, the AC is unable to blow hot air.
- Unit under-sizing – If the mini split is too small for your space, it won’t be able to blow enough hot air.
Fix
Set the temperature on Auto or Heat mode for it to blow hot air and replace the air filter if it’s dirty. Meanwhile, ensure your air con is the right size for your space.
4. Mitsubishi Mini Split Not Blowing Cold Air (Not Cooling)
If your Mitsubishi mini split won’t blow cold air, there’s the chance it’s due to a clogged filter or condenser, frozen coils, filthy outdoor unit, or low refrigerant, as I explain below:
- Clogged filter or condenser – if the air filter or condenser coils are dirty, they may prevent the AC from blowing cold air. So, the unit won’t get cold until you clean off the dirt clogging.
- Frozen coils – Dirt is not the only thing that makes it harder for the condenser/evaporator coils to cool your space. Frost also does the same, often relating to a lower temperature.
- Filthy outdoor unit – A filthy outdoor (too much dust, debris, and dirt) suffocates the outdoor unit. In the end, that prevents the AC from doing its primary job – cooling.
- Low refrigerant – Since the refrigerant absorbs heat during the compression process, the mini split cannot stay cold once the refrigerant level drops.
Fix
Clean the dirty condenser or filter (you can also replace the filter) and adjust the temperature to unfreeze the evaporator. In the meantime, declutter the outdoors for proper ventilation and call an expert if you suspect a leaky refrigerant.
5. Mini Split Won’t Turn Off
Sometimes a mini split will turn on and run nonstop because of either faulty wiring or low refrigerant. A defective wire connection sends the wrong signal, causing the AC to run nonstop.
And while a low refrigerant is associated with the unit not powering on or failing to stay on, it can also prevent it from turning off.
Fix
Call an expert to help you fix the wiring or refrigerant leakage.
6. Remote Control Not Working
The Mitsubishi mini split remote control often fails because it’s out of range or the batteries are dead or wrongly installed.
Fix
Try moving the remote close to the mini split. But before you do, replace its batteries and ensure you install them correctly.
Other Mitsubishi Mini Split Issues for Troubleshooting
Noise Problem
Some noises you may identify while the mini split is on include:
- Clicking or cracking sound – The sound often indicates the expected expansion of plastic parts. So, it doesn’t mean a fault.
- Hissing sound – This sound usually indicates a refrigerant flow. Subsequently, it’s not alarming.
- Mitsubishi mini split buzzing noise – While a buzzing sound may occur when the AC starts to run, it sometimes indicates an electrical fault. So, call an expert when the sound persists.
- Popping sound – A popping sound is also not alarming as it happens during defrosting. You don’t have to act in that case.
Odd Smell
Unusual smells you may notice while using a Mitsubishi mini split include:
- Musty or sour smell – The smell indicates the presence of mold, and you can fix it by rinsing the drain line and condenser drain.
- Fish smell – A fish smell indicates a possible refrigerant leak or electrical fault. Either way, you should call an HVAC expert.
- Vinegar smell – The smell of vinegar or a sweet odor often indicates a refrigerant leak. So, this is another case you should turn to an expert.
Indicator Lights
As far as the indicator lights go, a Mitsubishi mini split is likely to display any of these:
- 2 green lights on Mitsubishi mini split – Two green lights could indicate a working heat pump. It shows that the heat pump is working hard to keep up with the AC’s heating and cooling demands. You need to reset the air con to fix it.
- Blinking green light – A blinking green light often indicates an overvoltage. To fix that, you should reset your air conditioner.
Mitsubishi Mini Split Troubleshooting Codes
Lastly, the mini split may display a few error codes which you can troubleshoot. But first, you must interpret them. Common codes include:
- E0 (Remote control malfunctioning)
- P1 (faulty intake sensor)
- P4/P5 (drain line fault or sensor problem)
- P6 (evaporator coil fault)
- P8 (coil temperature or refrigerant line fault)
- P9 (communication error)
Fix
You can clear most of the Mitsubishi error codes by resetting the unit. Here’s how to reset Mitsubishi mini split air conditioner:
- Identify the reset button at the bottom of the mini split air conditioner or remote control and press it
- Alternatively, turn the power breaker off, then on to reset the AC
NOTE: You can visit Mitsubishi’s official page to type your current error code and get its recommended fix.
Important Questions:
Why is my Mitsubishi mini-split remote not working and how can I fix it?
How can I check if the batteries are causing the issue?
To check if the batteries are the problem, first, verify if they are exhausted. If they are, replace them with new ones. Additionally, ensure that the batteries are properly installed by checking the polarity (+, -) to see if they are correctly inserted.
Why is my Mitsubishi mini-split remote not working even if I press the buttons?
The remote control signal may not be received if it is operated too far from the air conditioner. Make sure to check the distance and move closer if necessary.
“The most common reasons for a Mitsubishi mini-split remote control not working are being out of range, dead batteries, or incorrect battery installation. If the remote control is not responding, try moving it closer to the mini-split unit. In many cases, this simple adjustment can resolve the issue. However, before doing so, it is essential to replace the batteries with fresh ones and ensure they are correctly inserted, paying attention to the polarity (+, -). By following these steps, you can effectively troubleshoot and fix the problem with your Mitsubishi mini-split remote control.”
What should I check if my Mitsubishi mini-split is not heating or cooling sufficiently?
Could high outside air temperature be reducing the cooling effect?
Yes, high outside air temperature can reduce the cooling effect of a Mitsubishi mini split. In hot weather conditions, the cooling capacity may be impacted. Consider additional measures to reduce the heat load in the room, such as using shades or curtains and minimizing the use of heat-generating appliances.
Could the use of a gas cooker or ventilation fan in the room be increasing the cooling load and causing inadequate cooling?
Yes, the use of a gas cooker or a ventilation fan in the room can increase the cooling load, resulting in inadequate cooling. Consider reducing or minimizing the use of such appliances while the mini split is operating.
Is the outlet of the outside unit blocked?
Ensure that the outlet of the outside unit of your Mitsubishi mini split is not blocked. Clear any obstructions or debris that might be obstructing proper airflow.
Is the filter dirty?
A dirty filter can restrict airflow and reduce cooling efficiency. Check the filter in your Mitsubishi mini split and clean or replace it if it is dirty.
Is the temperature setting correct?
Check the temperature setting on your Mitsubishi mini split to ensure it is set to the desired cooling temperature. Adjust the temperature if necessary.
If your Mitsubishi mini-split is not heating or cooling sufficiently, there are several factors you should consider. One possible cause could be a clogged filter or condenser, frozen coils, or a filthy outdoor unit. In order to address this, you can clean the dirty condenser or filter, and if necessary, replace the filter altogether. Additionally, adjusting the temperature settings can help unfreeze the evaporator and improve heating or cooling performance.
Another issue that may affect the efficiency of your mini-split is a blocked outlet of the outside unit. It’s important to declutter the area around the outdoor unit to ensure proper ventilation, which can greatly affect the cooling or heating effect.
In some cases, a low refrigerant level could be the culprit behind insufficient heating or cooling. If you suspect a leaky refrigerant, it is recommended to contact a professional to inspect and fix the issue.
It’s worth noting that faulty wiring or low refrigerant can cause the mini-split to turn on and run continuously without providing the desired heating or cooling. If you suspect any wiring issues or refrigerant leakage, it’s best to seek assistance from an expert to ensure proper repair.
Lastly, it’s important to consider the functionality of the remote control for your Mitsubishi mini-split. Oftentimes, remote control issues arise due to being out of range, dead batteries, or incorrect battery installation. To troubleshoot this, try moving the remote closer to the mini-split and replace the batteries, ensuring they are correctly installed.
By addressing these various potential issues, you can thoroughly troubleshoot any insufficient heating or cooling problems with your Mitsubishi mini-split system.
Why does my Mitsubishi mini-split make a popping noise and how can I address it?
How long does the defrosting process usually take?
The defrosting process usually takes several minutes to melt off the ice accumulated on the outside coil.
What causes ice accumulation on the outside coil?
Ice accumulation on the outside coil is a natural occurrence during the cooling process, and it needs to be melted off to prevent the unit from freezing up.
Is the popping noise alarming?
No, the popping sound during defrosting is not alarming and does not require any immediate action.
How can I address the popping noise?
The popping noise is not a fault, so the best course of action is to wait for the defrosting process to finish, which typically takes several minutes.
Why does my Mitsubishi mini-split make a popping noise?
The popping noise is likely due to the unit defrosting and ice accumulating on the outside coil.
If you hear a popping sound coming from your Mitsubishi mini-split, there’s no need to be alarmed. This sound typically occurs during the defrosting process and does not indicate a fault or problem with the unit. The popping noise is a result of ice accumulating on the outside coil, which needs to be melted off to prevent the unit from freezing up. While it may be slightly inconvenient, you don’t have to take any action when you hear this sound. Simply wait for the defrosting process to finish, which usually takes several minutes. Rest assured that this popping noise is a normal part of the mini-split’s operation and does not require any intervention on your part.
Why does my Mitsubishi mini-split make a hissing sound and is it a problem?
Should I be alarmed if I hear a hissing sound from my mini-split?
No, there is no need to be alarmed if you hear a hissing sound from your mini-split. As mentioned earlier, the hissing sound usually indicates a refrigerant flow, which is a normal operation of the unit and not a cause for concern.
Can a hissing sound indicate a refrigerant flow in a mini split?
Yes, a hissing sound in a mini-split can indeed indicate a refrigerant flow. The hissing sound is commonly associated with the movement of refrigerant inside the air conditioning system.
What could be causing my mini split to turn on and run nonstop?
A mini-split can turn on and run nonstop due to faulty wiring or low refrigerant. A defective wire connection can send the wrong signal, causing the AC to run continuously. Additionally, low refrigerant levels can also prevent the unit from turning off.
Is the hissing sound a problem?
The hissing sound is not necessarily a problem or an indication of a malfunction. It is a routine sound that occurs when the refrigerant flow is switched, and it does not point to any issues with the unit.
Why does my Mitsubishi mini-split make a hissing sound?
The hissing sound in a Mitsubishi mini-split is typically caused by the refrigerant flow being switched inside the air conditioning unit.
Sometimes, a Mitsubishi mini-split may emit a hissing sound, which can be concerning for homeowners. However, it’s important to note that this sound is usually associated with the refrigerant flow within the air conditioning unit. While a hissing sound may raise alarm bells, it is routinely the sound made when the refrigerant flow is switched, and it mostly does not point to a malfunction.
That being said, there are instances when a mini-split may turn on and run nonstop, which could potentially be attributed to faulty wiring or low refrigerant levels. Faulty wiring can send incorrect signals to the unit, causing it to run continuously. On the other hand, low refrigerant levels can not only prevent the unit from powering on or staying on but can also contribute to it running nonstop.
It is essential to keep in mind that a hissing sound, in itself, is generally not a cause for concern. While it usually indicates refrigerant flow, it is not alarming and should not immediately be considered a problem. However, if you notice any other accompanying issues such as the unit not powering on, failing to stay on, or experiencing cooling inefficiency, it is advisable to seek professional assistance to diagnose and address the underlying cause.
How can I troubleshoot power-related faults with my Mitsubishi mini-split?
Why won’t the mini-split turn off?
Inverter mini-splits are designed to run continuously, but if the Mitsubishi mini split won’t turn off at all, it could indicate a wiring fault or low refrigerant. Contact an expert to inspect the wiring connections and fix any issues. Additionally, have the refrigerant level checked and replenished if needed.
Could the compressor be overheating? (perhaps as a result of debris)
The compressor of the Mitsubishi mini split may be overheating due to debris accumulation. Inspect the outdoor unit for any debris, such as leaves or dirt, and clean it if necessary. Ensure proper airflow around the unit to prevent overheating and see if the problem persists.
Is the refrigerant level sufficient?
Insufficient refrigerant level can cause the Mitsubishi mini split to keep shutting off. Contact a professional to check the refrigerant level and recharge it if necessary. Low refrigerant level might indicate a leakage, which should be fixed as well.
Are the evaporator coils frozen? (due to blocked airflow)
If the Mitsubishi mini split keeps shutting off, it may be due to frozen evaporator coils caused by blocked airflow. Check for any obstructions or dirty filters that could be restricting the airflow to the unit. Clean or remove any blockages and see if the unit operates properly.
Is the ON-timer set?
Make sure to check if the ON-timer is set for the Mitsubishi mini split air conditioner. If it’s set, adjust or disable it accordingly to allow the unit to be operated.
Is the fuse blown?
Check the fuse for the Mitsubishi mini split air conditioner. If the fuse is blown, replace it with a new one of the same rating and see if the unit can be operated.
Is the breaker actually turned on?
Check if the breaker for the Mitsubishi mini split air conditioner is turned on. If it’s not, turn it on and see if the unit starts operating.
If you’re experiencing power-related faults with your Mitsubishi mini-split, troubleshooting the issue is crucial. One common problem is when the mini-split turns on and runs nonstop. This can be caused by faulty wiring or low refrigerant levels. A defective wire connection can send the wrong signal, causing the AC to continuously run. Similarly, low refrigerant levels, which are usually associated with the unit not powering on or failing to stay on, can also prevent it from turning off. In such cases, it is advisable to seek the assistance of an expert to help you fix the wiring or address any refrigerant leakage. Their expertise will ensure a proper resolution to the issue at hand.
Closing Thought:
Above are the most everyday Mitsubishi mini split troubleshooting problems you should be familiar with. You can thus turn to the guide when your mini-split suffers an issue you cannot fix but want to. Do that, at least before making a service call!
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