In this day and age, air conditioners have become a vital part of our lives and there’s a good reason why.  With the record breaking warm temperatures every summer, having a cool room to relax seems like heaven on earth. However, AC’s are a machine that need proper care and maintenance otherwise, you’ll have an AC running but not cooling.

In this article, we will analyze the reasons why your AC is not cooling and how to identify which issue you’re facing. Along with that, we will give solutions about how to deal with each problem and fix it so you are prepared.

Causes Behind An AC Running But Not Cooling

Worker Fixing AC Unit
Worker Fixing AC Unit

Here are 14 reasons why your AC is not cooling properly:

Dirty or Clogged Air Filter

Cause: One of the most common issues behind an AC running but not cooling is dirty or clogged air filters. Since the AC runs at a regular basis, it collects dust particles, pollen or pet hair, which after sometime clog the filter. This stops air from flowing through them and interferes with your indoor evaporator coil. Hence, it blocks the way of cool air from the outdoor condenser unit.

Solution: You can avoid this issue by regularly checking your air filters every 1 to 3 months. The frequency depends on how much you use the AC, whether you have pets or you live at a location with a lot of pollen or dust in the air.

How To Clean Filter:

Worker Fixing AC Running But Not Cooling Problem
Worker Fixing AC Unit
  1. Turn off the power of the AC
  2. Open the top cover and remove filters
  3. Wash them thoroughly with water
  4. Air dry them
  5. Place them back in the AC

Thermostat Problems

Cause: Sometimes when you have your AC running but not cooling and you check your inner and outdoor unit for issues, there are none. If so, then you should check your AC’s thermostat. Problems with the thermostat can lead to issues with your AC’s overall functioning and cooling. You can usually adjust the thermostat from its power source.

Solution: It’s important to ensure that the thermostat remains at a cool setting and not heating. Change the settings to auto, this way the AC will change to a cooler temperature if it’s getting warm indoors. Otherwise, just make sure you have set a temperature that’s most suitable for you. In case, the thermostat is out of order, then contact a professional to come and fix it.

Dirty or Blocked Condenser Coils

Cause: The condenser coils are located on the outdoor unit of an AC, it helps dissipate heat from the air and sends it outside. However, to do that it must remain clean otherwise it becomes less efficient. Otherwise, you will be stuck with the problem of your AC running but not cooling. It gets dirty with time as it mostly stays humid and this causes debris, mold and mildew build-up which reduces the AC’s cooling efficiency.

Solution: In order to clean your condenser coil you must wash it using a hose or a coil cleaner. For wall units, make sure you use Our AC Cleaning Kit to minimize debris fallout. However, if it needs repair then it’s best to consult a professional.

Refrigerant Issues

Cause: Refrigerant is a chemical that circulates through the coil and helps your AC transfer heat trapped indoors to outdoors. Your AC will not work if you are low on refrigerant gas and it may stop cooling. The reason for low refrigerant is due to insufficient filling during installation or leakage.

Solution: Once you identify the actual issue for your ac running but not cooling, then it’s best to call a professional technician to fill the refrigerant. This is because they have sufficient technical knowledge and equipment to fix the problem without any errors.

Electrical Issues

Cause: This is another significant cause of AC running but not cooling. Electric issues with your AC include damaged wiring, defected compressor, a faulty capacitor or other small defected parts. All these issues can stop your AC from providing proper cooling. Here’s an article on our website about how to replace a capacitor.

Solution: If you notice a problem with the AC’s compressor then you might have to replace it. It’s one of the most expensive parts of the AC so just be prepared. However, you would need professional help to solve this.

Air Duct Leaks And Poor Insulation

Cause: If the air ducts of your AC are either poorly insulated or leaking, then your AC may not provide the desired temperature. It may be because the cool air may not reach your home. It can be due to poor insulation or if the duct is damaged.

Solution: In order to solve this problem of your ac running but not cooling, you would need to call a qualified technician. They can check where the damage is and ensure proper insulation and repair it for you.

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Oversized or Undersized AC Unit

Cause: Sometimes you purchase the wrong size of AC for your space. It’s either oversized or undersized for your living space and therefore may not provide proper cooling. Undersized units cannot cool more than their capacity and oversized units may cool a bit more than your preference, also causing waste of electricity.

Solution: Before purchasing an AC, make sure to consult a professional. They mainly calculate the load the AC can bear in accordance to the size of the place they will be set up.

Lack of Maintenance

Cause: Another common reason why you have your AC running but not cooling is because of lack of maintenance. Over time, dirt and dust is collected in your AC. Therefore, it’s important to get it checked regularly for maintenance in order to prevent it from further problems.

Solution: You need to call a professional to check your AC for maintenance issues. During this checkup they can look for potential problems and fix them before extensive repair is needed.

Frozen Evaporator Coil

Cause: Sometimes the evaporator coil in your indoor unit tends to freeze, causing cool air to stop from entering your living space. The result is the Ac running but not cooling. This is usually because of an insufficient flow of air caused by low fan speed or blocked air filters.

Solution: If this happens then it’s best to turn the AC off and wait for the ice to melt. Once it has melted then wash your clogged air filter, put them back in the AC and turn it on.

Blocked Vents or Registers

Cause: Your AC’s registers tend to get dirty with time, this causes them to block. This may happen if you don’t clean them regularly. Blocked registers cause an increase in electricity bill as they make your AC work much harder. When the machine is exhausted, you may find your ac running but not cooling.

Solution: In order to avoid this issue you need to regularly clean your AC’s registers. You can clean them by using a vacuum cleaner to remove all the dirt and debris to unblock them.

Heat-Generating Appliances

Cause: Electronic devices, ovens or stove tops mostly generate heat. If your living area has an open kitchen and the oven and stove are being used, then the AC might not provide the cooling that it otherwise would.

Solution: Try to minimise usage of appliances that generate heat at day time when the sun is blistering and it’s actually hot outside. Try to use appliances around the house that generate less heat. Also ensure that your thermostat is placed away from heat so it can work properly.

Debris Around the Outdoor Unit

Cause: The outdoor units of ACs collect a lot of dirt, leaves and dust. This causes a decreased airflow that can lead to less cooling.

Solution: The outdoor unit should be regularly checked and cleaned. This ensures proper airflow.

Age of the AC Unit

Cause: AC units tend to depreciate with time. The older they get the more they struggle to provide proper cooling.


The best way to solve this problem is by purchasing a new unit that saves energy and is cost effective at the sametime.

Problems with the Exterior Fan Motor Could Be the Culprit

Cause: The hot air in your home is released outside your house by the fan of your outdoor unit. However, sometimes a problem with the fan may cause it to be inefficient. This may trick the system into ac running but not cooling.

Solution: The best way to solve this problem is by taking help of a professional who can fix the issue.


When you have your AC running but not cooling, it’s important to go in-depth of what the actual cause can be and come up with the right solution. In this article, we have guided you regarding what problems you can face, their causes and solutions. Just remember that there are a few problems that you can solve on your own, otherwise it’s best to call a professional. Find A Pro Near You Here!

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For any repairs, installations, builds, or questions; We recommend you to hire a professional. Find A Pro Near You Here!

Frequently Asked Questions FAQs

My AC is running, but it’s giving out warm air. How can I fix it?

If your AC is giving out warm air then the first step you take is to clean it. Start by cleaning the filter, vents and vacuum registers to clean dust and check the outer unit for dirt and debris as well. If the issue persists then it’s best to call a professional to identify and solve the issue.

Is it possible that electrical problems in the AC unit can cause it to run but not cool properly?

Yes, there are different electric issues that your AC can face such as damaged wiring, faulty capacitor or a compressor that is not working properly. However it’s best to get help from a professional on this issue as they have the optimum knowledge about them.

How often should I replace my air filter, and can a dirty filter affect cooling?

You should replace air filters every 1 to 3 months. It depends entirely on usage. A dirty filter can get clogged hence, restricting the flow of air. This contributes to making it a tough task for your AC to cool your home.