Every DIY Mitsubishi owner needs an easy-to-follow Mitsubishi air conditioner troubleshooting guide on their side. Why? That’s to troubleshoot issues and faults as soon as they arise!
Common Mitsubishi air conditioner faults and issues you can troubleshoot are the AC not turning on or off, not cooling, not heating, heat mode not working, keeps turning off, and the fan not working. Others include the AC not responding to the remote and blinking green light.
As you’ll notice in this guide, most AC fixes are DIY. So, you won’t have to pay someone to get your Mitsubishi aircon back working. And as you’ll discover from the fixes, some issues are equally avoidable.
We’ll discuss the nine problems common to Mitsubishi air cons and their solutions.
Let’s get started!
In a rush? See below a summary guide for troubleshooting common Mitsubishi air conditioner problems.
Quick Mitsubishi Air Conditioner Troubleshooting Guide
| – | Problem | What To Check (Likely Reason) | Recommended Fix |
| 1. | AC Won’t Turn On Or Start (Mitsubishi Air Conditioner Not Opening) | Tripped breaker or isolator switch, faulty or overloaded outlet, damaged power cord, nonresponsive remote or faulty capacitor, compressor or thermistor | Reset the breaker or isolator switch if tripped, avoid overloading the outlet, replace it if faulty, and change the remote’s battery if exhausted. And if the capacitor, compressor, or thermistor is defective, replace it |
| 2. | AC Won’t Turn Off | The wrong setting, dirty filter or coils, slow speed fan, faulty wiring, or low refrigerant | Turn off the fan’s limit switch, clean the dirty filter and coils, and set the fan on medium/high speed. Call an expert to check and fix faulty wiring or low refrigerant |
| 3. | AC Won’t Cool | Clogged filter, unmaintained outdoor, wrong AC size, low refrigerant, or faulty fan motor, compressor, or electronic control board (ECB) | Replace or clean a clogged filter, declutter the outdoors and get the right AC size. Ask for expert help to fix refrigerant leakage and replace a faulty fan motor, compressor, or ECB |
| 4. | AC Won’t Heat | A low-temperature setting, AC under-sizing, wrong mode, or dirty filter | Raise the AC’s temperature to match the room temperature and set it on Auto/Heat mode. Replace the dirty filter and upgrade the AC if its small |
| 5. | Heat Mode Not Working | Tripped breaker, dirty outdoor, defective fuse, low refrigerant, or faulty heat pump | Reset the breaker if it’s tripped, declutter the filthy outdoors, and replace a defective fuse. And if you suspect a low refrigerant or faulty heat pump, call an expert |
| 6. | AC Keeps Turning Off | Power supply fault, low refrigerant, faulty or incorrectly positioned thermostat, oversized AC, dirty filter, or broken motor | Fix the power supply fault (with the help of a technician). Replace the thermostat if it’s faulty and position it correctly. Ensure the AC is the right size, and replace a dirty filter or broken motor |
| 7. | Fan Not Working | Wrong fan mode or setting or bad thermostat or fan motor | Choose a medium/high speed and replace the thermostat or fan motor if any of them is faulty |
| 8. | AC Won’t Respond To The Remote | The remote is too far or dead or wrongly fitted batteries | Move the remote close to the AC, replace its battery if they are dead, and fit them accordingly |
| 9. | AC Blinks Green Light | Voltage overload, refrigerant leakage, dirty filter, electrical fault, or bad compressor | Reset the AC and if the blinking won’t stop, replace the filter and ask an expert to help you fix a refrigerant leak, electrical vault, or bad compressor |
9 Common Mitsubishi Air Conditioner Problems and Their Troubleshooting Guide
Is your Mitsubishi air conditioner not working? Then, here’s how to troubleshoot the most typical Mitsubishi air conditioner problems DIY:
1. Mitsubishi Air Conditioner Not Turning On (Mitsubishi Air Conditioner Not Starting)
A Mitsubishi AC won’t turn on or start for different reasons. The commonest ones are as follows:
- Tripped breaker or isolator switch – A power overload will trip the circuit breaker or isolator switch. So, it’s vital that you check them out and reset them accordingly.
- Faulty or overloaded outlet – If the electric outlet is defective (which you can know if it doesn’t show continuity on a multimeter), the AC won’t turn on until you change it. Similarly, if you’ve plugged in many appliances in the same outlet, the AC may not start until you reduce the load.
- Faulty power cord – Use the multimeter to examine the AC power cord’s continuity. If the cable has no continuity, the AC won’t turn on until you replace it.
- Nonresponsive remote – If the remote control is not working, the AC won’t turn on when you press it. So, check the batteries, replace them if they are exhausted, and ensure you fit them correctly.
- Faulty capacitor, compressor, or thermistor – Lastly, have an expert examine the capacitor, compressor, and thermistor for fault. If any is defective, the expert will advise you to replace it.
2. Mitsubishi Air Conditioner Not Turning Off
Something must be a miss if your Mitsubishi air con runs nonstop. In most cases, the AC won’t turn off due to any of these reasons:
- Wrong setting – If the fan setting is ON, the AC will run nonstop until you cut off its power supply or turn off the setting. In some cases, the fan is set on ‘Auto’ mode, similar to being on.
- Dirty filter or coils – Sometimes, dirty filters or coils don’t prevent the AC from turning on but turn off. So, inspect the filter and coils for excessive dirt and clean them.
- Slow-speed fan – Ensure your fan runs on medium/high speed. If it’s running at a slow pace, it may not stop.
- Faulty wiring – If there are broken or loose wires, the AC may run nonstop. So, consider asking for an expert’s help to identify and fix faulty wiring.
- Low refrigerant – A low refrigerant due to leakage may also prevent the AC from turning off. But since its diagnosis isn’t easy, talk to an expert.
3. Mitsubishi Air Conditioner Not Cooling
A Mitsubishi air conditioner may fail; to blow air because of any of these issues:
- Clogged filter – For cooling to occur, there must be a steady airflow. That, however, won’t be the case if the air filter is dirt clogged. If so, you must replace it (if disposable) or clean it (if reusable).
- Unmaintained outdoor – Too much outdoor filth, including debris, dust, pollen, and unpruned branches, makes it hard for your outdoor unit to breathe, thus preventing cooling. You need to clear the outdoor filth if that’s the case.
- Wrong AC size (undersized or oversized) – If the AC is smaller or bigger than the space it’s cooling; it won’t be able to cool effectively. That’s why you should get a Mitsubishi AC that matches your area.
- Low refrigerant – Damage to the AC and poor installation can cause refrigerant leakage. Once that happens and the refrigerant level drops, the AC is unable to cool. You’ll need an expert’s help here.
- Faulty fan motor, compressor, or ECB – Lastly, if the fan motor, compressor, or ECB (electronic control board) is defective, your AC won’t cool until you replace it with an expert’s help.
4. Mitsubishi Air Conditioner Not Heating (Mitsubishi Air Conditioner Not Blowing Hot Air)
Sometimes, the Mitsubishi air con may fail to blow hot air, thus making it colder than usual, and it’s often due to these reasons:
- Low-temperature setting – If the thermostat setting is lower than the room temperature, the AC won’t blow hot air. So, check the setting and adjust it.
- AC under-sizing – If the AC is smaller than your space, it won’t blow enough hot air. So, you’ll need to upgrade your Mitsubishi AC if it’s too small for your area.
- Wrong mode – Your AC won’t blow hot air if it’s in DRY or COOL mode. You need to check if that’s the case and turn the setting to Heat/Auto mode to allow the unit to start heating.
- Dirty filter – Consider changing or cleaning the air filter if it’s dirt clogged to encourage heating. The AC won’t heat up if the filter is dirty.
5. Mitsubishi Air Conditioner Heat Mode Not Working
The heat pump at times won’t blow hot air, and it’s often due to:
- Tripped breaker – Once the breaker trips, the heat pump’s power supply is cut off, preventing it from running. If that’s so, reset the breaker.
- Dirty outdoor – A filthy outdoor only makes it hard for the heat pump to work. You’ll need to clear the debris and filth to remedy the situation.
- Defective fuse – The thermal fuse will blow up due to a current overload. So, examine it with a multimeter (or multitester) and replace it if it’s faulty.
- Low refrigerant – Consider talking to an expert to help detect and fix a refrigerant leakage.
- Failed heat pump – If none of the above remedies work, consider getting a new heat pump or replacing the AC.
6. Mitsubishi Electric Air Conditioner Keeps Turning Off (Won’t Stay On)
Occasionally, the Mitsubishi AC would turn on but fail to stay on. The reasons to explain that include:
- Power supply fault – Issues such as faulty wiring, short circuits, loose power cord, and failing thermostat and control board will cause your AC to turn off. You’ll need an expert’s help to diagnose and fix the issue.
- Low refrigerant – You also need an expert to check and fix the refrigerant level.
- Faulty or incorrectly positioned thermostat – If the thermostat is defective (won’t show continuity) or incorrectly set, your Mitsubishi AC won’t stay on. Thus, replace the thermostat if it has no continuity and re-position it if it’s out of position.
- Oversized AC – Check the AC size to ensure it’s not too big for your space. If it is, it will need replacing lest it won’t stay on.
- Dirty filter – Examine the air filter for dirt clogging and replace /clean it. A dirty filter generally makes it hard for the AC to stay on.
- Broken motor – Inspect the motor and replace it if it’s damaged. A broken motor makes it hard for the AC to run continuously.
7. Mitsubishi Air Conditioner Fan Not Working
Consider these issues if your Mitsubishi AC fan is not working:
- Wrong fan mode or setting – Ensure the fan is on medium/high speed and not on low speed or auto mode. Low speed and auto mode make it harder for you to notice the fan working, even if it is.
- Bad thermostat or fan motor – Inspect the thermostat and fan motor for malfunctioning. If any of them is broken-down, replace them to allow the fan to work fine.
8. Mitsubishi Air Conditioner Not Responding to Remote
Check out these issues if your Mitsubishi AC won’t respond to the remote control:
- Remote-to-AC distance – The AC won’t respond to the remote if the two are far apart. It’s best to move close to the AC before pressing the remote.
- Battery power and polarity – If the remote still won’t work, replace its batteries as they could be dead. And as you change them, ensure you fit them the right way, keeping their polarity in mind.
9. Mitsubishi Electric Air Conditioner Blinking Green Light
Lastly, consider these issues if your air conditioner is blinking green light:
- Excess voltage – Often, the Mitsubishi AC goes into a self-shut mode once it detects an overvoltage. The shelf shut process is often initiated with a green blinking light. If so, you should master how to reset Mitsubishi air conditioner.
- Refrigerant leakage – Though rare, sometimes the green light blinks to indicate a refrigerant leakage. An expert, however, will help you if that’s the case.
- Dirty filter – Also, check the air filter for filthiness. If it’s dirty, consider replacing or cleaning it to stop the blinking.
- Electrical fault – The blinking may also indicate an electrical fault which an expert can help you diagnose and correct.
- Bad compressor – If none of the four issues is the matter, consider replacing the compressor as it could be faulty. You’ll need an expert’s help to do it.
Closing Remarks
Now you have an informative Mitsubishi air conditioner troubleshooting guide to use. So, whenever your Mitsubishi air con doesn’t start, turn off, heat, cool, stay on or suffer any other malfunction, turn to this troubleshooting guide to see what you can do to remedy the issue. Only when you cannot troubleshoot it should you call an HVAC expert.
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