The summer is here, and the last thing you want is your Mitsubishi mini split not blowing cold air. The mere thought of the hot season without a cooling air conditioning unit is depressing.
Often, a Mitsubishi mini split fails to blow cold air because of a clogged air filter, wrong temperature mode, frozen or dirty coils, power disruption, unmaintained outdoor, refrigerant leakage, drainpipe clogging, or a faulty compressor, thermistor, or fan motor.
Your job as a DIYer is to determine which of those issues stops your mini split from cooling and take the right course of action. Don’t worry about troubleshooting, as I’ll walk you through it.
We’ll discuss the ten issues and their most recommended fixes. I’ll also mention the problems you should leave to an HVAC professional, mainly those involving a component failure that requires replacing.
Let’s get started!
In a rush? Consider the quick troubleshooting guide below to fix your non-cooling Mitsubishi mini split.
Quick Troubleshooting Guide for A Mitsubishi Mini Split Not Blowing Cold Air
| – | Likely Cause | Recommended Fix |
| 1. | Clogged Air Filter | Vacuum or wash the dirty filter with lukewarm soapy water |
| 2. | Wrong Temperature Mode | Switch the temperature mode from HEAT to COOL, Auto, or Dry where applicable |
| 3. | Frozen Or Dirty Coils | Clear the frost from the coils and if they are dirty, clean them |
| 4. | Power Disruption | Check for a tripped breaker and flip it back on and if the fuse is blown up, replace it |
| 5. | Unmaintained Outdoor | Disassemble the outdoor unit and clean its internal components to get rid of dust and dirt |
| 6. | Refrigerant Leakage | Call an HVAC professional if you suspect the coolant/refrigerant is leaking |
| 7. | Drain Pipe Clogging | Call an HVAC professional if you spot clogging in the drainpipe. That includes dirt, algae, and debris |
| 8. | Faulty Compressor | Have an expert inspect the outdoor unit to determine if the compressor is faulty and needs replacing |
| 9. | Defective Thermistor | Also, have an expert check the thermistor in the outdoor unit and fix it if it’s faulty |
| 10. | Broken Fan Motor | Replace the AC’s fan motor if it’s broken |
How to Troubleshoot a Mitsubishi Mini Split Not Blowing Cold Air?
Now, consider the ten issues below if you want to troubleshoot a Mitsubishi mini split that won’t cool:
1. Mitsubishi Mini Split Not Getting Cold Due to a Clogged Air Filter
Generally, most air conditioning systems fail to cool because of a dirt-clogged air filter, not just Mitsubishi mini splits. Remember, your mini split must have adequate air exchange to cool your space.
That, unfortunately, won’t happen if the air filter is excessively filthy. It shouldn’t be dirt-clogged.
Fix
Start by checking the air filter for dirt clogging. You’ll need to remove your indoor unit’s front panel to access the air filter. If it looks dirt-caked, consider cleaning it. But first, detach the filter and pull it out to clean it.
You can vacuum if it’s slightly dirt-clogged, but if the clogging is heavy, wash it with lukewarm soapy water and dry it before use. Remember, Mitsubishi recommends cleaning the air filter every 3-6 months and replacing it after every 12 months.
2. Incorrect Temperature Mode
A Mitsubishi air conditioning system’s two temperature modes are essential for cooling space: Cool and Auto. As the name suggests, the ‘Cool’ mode allows the unit to start cooling. So, it’ll blow cold air, which is what you want.
‘Auto’ mode, on the other hand, switches the air conditioner according to the room temperature. If the room is sweltering, the air conditioner will blow cold air. If it’s freezing, the unit will blow hot air.
But now, if you have selected the ‘HEAT’ mode, your mini split will blow hot air instead of cold air, which becomes a problem. So, check to see what mode is on.
Fix
Check to see if your mini split is on ‘HEAT’ mode. If it is, switch it to ‘COOL’ mode, AUTO, or even Dry if it applies to you to allow it to cool.
3. Frozen or Dirty Coils
The evaporator and condenser coils are vital for cooling. The air conditioner won’t blow cold air if they are dirty or frozen. Let’s start with dirty coils.
If the coils, mainly the condenser coil, accumulate dirt, dust, or mold, the particles will stop hot air from circulating above the condenser coil. That means there won’t be a way to get the heat out of it, resulting in a hot room.
And when it comes to frozen coils, especially the evaporator coil, the ice blanket restricts airflow the same way as the dirt clog, resulting in a non-cooling unit.
Fix
Inspect the condenser coil for dirt clogging. If that’s the case, clean it with the rest of the condenser. Do it similarly to the air filter (discussed above).
As for the evaporator coil, inspect it for frosting. You’ll need to open the mini split front panel to do it. Once you find some ice masses, thaw them by setting up the fan at high speed.
Of course, that means plugging back the air conditioner. You can also try cleaning the ice mass manually.
4. Mitsubishi Mini Split Not Blowing Cold Due to Power Disruption
It’s a no-brainer that your mini split won’t work if there’s a power disruption. And when speaking of not working, we are also discussing not cooling.
So, you can’t overlook this possibility, and there are two critical considerations.
- Circuit breaker – Check the circuit breaker for possible flipping/tripping. A flipped circuit breaker disrupts the mini splits power supply, affecting cooling, heating, and other functions.
- Fuse – Inspect the ACs fuse for blowing up. If it’s blown up, the air conditioner won’t cool.
Fix
Reset (flip it back on) the circuit breaker if it’s flipped/off. As for the fuse, use a multimeter device to check its continuity. If it shows none, replace it.
5. Unmaintained Outdoor
Your outdoor unit shelters the condenser, compressor, and fan, among other vital components. So, it requires the highest level of maintenance.
If you fail to clean it afterward, it will accumulate dust, debris, mud, and other particles that will block its airflow. In the end, your AC is unable to cool as it should.
Fix
It’s vital that you check your outdoor unit for dirt clogging. You’ll need to open up its top panel. Once you notice that the unit’s internal components are dirt clouded, use a vacuum or soft brush to clean them.
Avoid water in this case, as there are electrical parts, but you can use a damp cloth to dust off the electrical components (while the unit is off and unplugged).
6. Mitsubishi Mini Split Not Cold Enough Due to Leaky Refrigerant
A lot of the mini splits cooling depends on the refrigerant. This liquid coolant absorbs the extra heat from the circulating air. It is, however, unable to do that once its level drops.
So, you ought to check for possible refrigerant leakage, which you can tell if there’s dampness around the outdoor unit and an odd smell. Moreover, the unit won’t cool as a result.
Fix
Once you suspect the coolant is leaking, call an HVAC professional. It’s generally hard to establish the source of the coolant leakage and fix it accordingly.
7. Drainpipe Clogging
Each mini split features a drainpipe that collects moisture. Due to the excess dampness, algae, dirt, and debris may build up and clog the drain pipe. Once that happens, your air conditioning unit won’t cool.
Fix
Inspect the drain pipe for debris, dirt, or algae clogging and once you spot that, call an HVAC professional. The professional will clear the clogging and advise you on how to prevent its recurrence.
8. Faulty Compressor
We cannot talk about a non-cooling mini split without highlighting the centerpiece of the whole unit, the compressor. The compressor circulates the coolant between the indoor and outdoor units.
If it’s damaged or worn out, it won’t be able to perform its job, which means your air conditioning unit won’t blow cold air.
Fix
A faulty compressor mostly requires you to replace the entire outdoor unit. And since it’s easy to misdiagnose, it’s best to ask an HVAC expert to look at the unit and advise you accordingly.
9. Mitsubishi Mini Split Ac Not Blowing Cold Air Due to A Defective Thermistor
You should also examine the thermistor in your outdoor unit to determine if it’s faulty. Generally, the thermistor transmits a signal to the cooling compartment for cooling to take place.
If it’s defective, there won’t be any signal delivery to influence cooling. And as a result, your unit won’t cool.
Fix
You should let an expert HVAC technician check the thermistor and determine if it’s faulty. If it is, the expert will help you fix it.
10. Broken Fan Motor
Lastly, consider that you might have a broken fan motor if your mini split still won’t blow cold air. Once the motor breaks or wears down, it’s unable to run correctly, and the mini split will fail to blow cold air.
Fix
Inspect the fan motor in your outdoor unit to see if it’s broken. If it is, contact the nearest Mitsubishi dealer for a replacement and technical assistance.
People Also Ask
1. Why Is My Mitsubishi Split AC Not Cooling?
A dirt-clogged filter is one of the typical reasons Mitsubishi mini splits fail to cool. Check the air filter to determine if its dirt is clogged. If it is, clean it.
Other possible reasons include a frozen coil, refrigerant leakage, faulty compressor, unmaintained outdoors, and the wrong temperature mode.
2. Why Is My Split Air Conditioner Running but Not Cooling the House?
Your split air conditioner can be running but cannot cool your house due to a clogged air filter or condenser coil, frozen evaporator coil, an unmaintained outdoor unit, or refrigerant leakage.
3. How Should I Reset a Mitsubishi Mini Split?
You can hard reset your Mitsubishi mini split by unplugging it from the power for one minute or more or by flipping off the power breaker for the same period.
Alternatively, press the reset button on your mini split, especially if you want to clear an error code.
4. What Do the Two Green Lights On Mitsubishi Mini Split Mean?
Often, the two green lights pop up on a Mitsubishi mini split to indicate that the heat pump is a few degrees away from reaching its preset temperature.
So, you may have to wait to see if the lights will go off. If not, then they could suggest a fault which you should check.
5. Why Is My Mini Split Not Getting Cold?
Several reasons could explain why your mini split is not getting cold. It could be due to a frozen coil, dirty condenser, refrigerant leakage, wrong temperature mode, a faulty compressor, or a broken motor, to name a few.
6. How Do I Tell When My Mini Split Runs Low On Refrigerant?
One way to know if your mini split is low on refrigerant is if it does not cool. You can also tell if there’s a refrigerant leakage due to dampness around the outdoors or an odd smell.
Closing Thought On Mitsubishi Mini Split Not Blowing Cold Air
The next time your Mitsubishi mini split won’t cool your space, check the air filter for clogging, the refrigerant for leakage, and the outdoor unit for dirt.
Don’t forget, however, issues like power disruption, drainpipe clogging, faulty compressor, defective thermistor, and broken motor.