Split AC not cooling but fan is running? 5 fixes

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So, how can you fix a split AC that is not cooling yet the fan is running?

Well, that is exactly what I will be sharing with you in this split ac troubleshooting article.

I hope it will help you fix your air conditioner and make it start cooling again properly

Let’s jump in:

Split AC not cooling but fan is running – What to check and recommended fixes

If your split AC fan is running but not cooling, check the filter, refrigerant levels, thermostat settings, and more. Get your cooling unit working again with the following tips.

There could be a couple of reasons making your split air conditioner not cool yet the fan appears to run.

Here they are and what you can do to correct every potential cause of the issue:

The thermostat settings might be wrong – check and correct

I know it sounds unbelievable but yes, the problem may be due to bad stat settings so can you start by checking the thermostat settings you have set.

Specifically, you want to verify that you have set the stat to your pre-determined temp setting.

Next, you want to confirm that it is set to cooling mode- it won’t cool maximally, if for example you have selected dry mode.

What I’m saying in a nutshell is this: If your thermostat is not set correctly (or it has malfunctioned), then it could lead to the split AC not cooling but fan is running issue so begin by ensuring the settings are right.


The air filter might be dirty – clean it

This is one of the most likely causes of the air conditioner not blowing cold air but running fault (not blowing cold air but just fan air)

You see, if you have not cleaned the air filter recently, then the dust and debris that could be in it tend to hamper the airflow.

And that in turn harms the cooling performance, which is probably why your unit is not cooling optimally despite the fan operating normally (it is possible it is cooling but not enough for you to feel comfortable).

Suggested repair

Clean air filter on your minisplit thoroughly-keep in mind that the filter is typically found on the front facing panel of your indoor unit.

As regards how to clean it, you can simply go the vacuuming route (you’ll need a brush attachment) to get rid of dust, dirt, or debris you see.

You can otherwise wash it in a basin(or even a sink) with lukewarm water- add any good mild detergent, if it is extremely soiled.

Don’t forget to let the filter completely air dry (before you re-install it).

Also, consider replacing the filter if it seems damaged when you pull it out.

Quick Tip: It is a good idea to clean your air filter about once every 1 to 3 months (at least), depending on environmental factors and your usage.


The issue might be low refrigerant – have it checked

Next, if your AC is running low on refrigerant- and it is a possibility as well- then you might notice poor cooling performance.

If you’re wondering what could make the refrigerant to reduce, oftentimes it is because of a leak somewhere(a slow leak along the refrigerant lines) or even improper installation.

Sadly, only a qualified HVAC pro can help check refrigerant levels(and recharge, if necessary).


The compressor may be defective- check and replace

Not everyone can do this but it’s another fix worth giving a shot..

Remember a ‘sick’ compressor means cooling problems when you power on your AC unit (A/C fan will be running as it should but the compressor won’t kick on).


Well, the compressor pumps refrigerant through the AC so if it has malfunctioned, no satisfactory cooling will take place(and the temp won’t be dropping).

So, what’s the solution?

Now, if it is not a repair you can do, get a repairman to come in and test the compressor (and change it, if it is already damaged).

Pro Tip: You should check the compressor for proper voltage as well as power supply. That’s because if compressor isn’t running on adequate(optimum) power, then it is unlikely to cool the room effectively.


You are overworking the AC

Another possible reason behind your Mini Split AC cooling woes is using a wrongly-sized unit for the space you’re attempting to cool (not enough BTUs).

Yes, it is not something you can ignore because some folks are often trying to cool too large a space with a unit that is sized for a smaller area..

That means it will be struggling awfully to reduce the temp to your set level since it has inadequate cooling power.

Of course, the remedy here is to swap out the unit with one that is designed to cool the square footage that you’re trying to cool.



Split AC not cooling but fan is running (window split ac not cooling but fan is running) – Recap of what to check

Check the following if you’re trying to fix the window ac not cooling but fan is running problem:

  • Thermostat- ensure correct settings
  • The filter- clean filters, if dirty
  • Refrigerant- Lack of adequate refrigerant can cause it. Have it checked and recharged.
  • The compressor – test and replace (a pro should do this)
  • Get a unit with recommended BTUs for the space– Undersized unit won’t drop temp as you had hoped.

Good luck with your troubleshooting.



Mitsubishi mini split troubleshooting guide

Mitsubishi mini split error codes explained (and possible fixes) 

AC power consumption vs temperature – what to know

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