15 Reasons Your Air Conditioner Is Not Cooling (+Fix)

It is frustrating and stressful if an air conditioner does not cool down your house during the scorching summers. An air conditioner not working in the summer is the least you want. So, you must quickly identify the problem faster for a comfortable environment. 

Your air conditioner might not be cooling due to various factors, including dirty air filters, blocked condensers, dirty or frozen coils, and low refrigerant. You must regularly clean the filters and ensure no refrigerant leakage. Regular maintenance of the unit can prevent these issues.

The list continues. There are many more reasons behind an air conditioner not cooling. This article will explore all the possible reasons behind it and how to troubleshoot them. 

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Air conditioner running but not cooling – What should I know?

An air conditioner is meant to eliminate the hot air and humidity from your house and spread cool air to comfort you and your house members. 

But, it can be quite frustrating if it cannot do the only duty it is supposed to. 

When your air conditioner is not cooling your house, you should ask yourself two questions:

  • How long has the air conditioner been like this?
  • What is the outside temperature of your region?

Some people must understand that an air conditioner can cool your room to a certain level. 

For example, if you live in areas like Orange County (California) and Seminole County (Florida), the temperature surpasses 93°F. 

So, your air conditioner will operate normally only if the temperature is below this range. 

Once the outside temperature exceeds 93 degrees, the air conditioner cannot cool down your room.

So, before you suspect any problem and try troubleshooting the problem, make sure that the problem is real. 

If the temperature is not extreme, but the air conditioner still cannot cool your house, check out the situations we shared below. 

1. Check the thermostat

Your air conditioner is running efficiently but does not cool your house properly. You need to check the thermostat once. 

Someone or you may have changed your thermostat’s temperature or fan setting. 

You only need to set the thermostat to COOL instead of FAN or HEAT. 

Sometimes, the setting is set to AUTO. When the setting is AUTO, the fan will only turn on during the AC cycles. 

Once the cycle is complete, your fan will turn off, and the unit will no longer cool your room.

If the settings are corrected, check whether the air conditioner gives enough cool air. 

If the problem remains, there is some other problem. 

Your air conditioner is not cooling could also be due to dead thermostat batteries. 

If the thermostat is blank, consider checking the batteries and changing them. 

2. Dirty air filters

Generally, you must change the air filters every 3-4 months. 

If you don’t, it will accumulate all the dirt, debris, and air particles, creating an obstacle to airflow. 

The dust accumulation will be so thick that it won’t flow the air properly, therefore not allowing the unit to cool your house. 

It will also cause the coils to freeze. 

To confirm the problem, open the cover plate of your unit, take out the filter, and see if you can see anything through it. 

You must replace it with a new one. Or, you can wash it if the product is reusable and washable. 

Wash it, dry it, and put it back. 

While installing, ensure the arrows are in the airflow direction. 

You should replace a standard 1-inch air filter once a month. 

3. Clogged coils

An air conditioner has an indoor air handler and an outdoor condenser. Both have coils that are pivotal to cooling your home to the best. 

The outdoor condenser coil will release the heat from the unit. 

But if the coil gets clogged, it cannot release the heat, keeping your house warm despite running the unit. 

You can check the coil easily by going outside and watching the condenser. 

Check for plants and shrubs as they create dirt and debris and block the airflow the most. 

Make sure there has to be a 2 to 3 feet distance between the trees and shrubs and the condenser. 

If you find dirt and debris, wash the unit from the outside using a hose. 

The indoor air handler has evaporator coils to remove the heat from your house. It will become clogged and dirty over time. 

Changing the air filters can prevent this. 

It is better to let the HVAC expert team clean the indoor coils. 

They are more delicate than outdoor ones and need special maintenance. 

4. Frozen evaporator coils

The indoor air conditioning unit will have an evaporator coil. 

If the indoor unit is a furnace, the evaporator coil will be in its cabinet outside the unit. 

If the indoor unit is a fan coil, like a part of the heat pump, the evaporator coil will be inside the fan coil cabinet. 

Warm indoor air passes through this coil, where the heat and humidity are removed from the air. 

After that, cool air is distributed throughout your house. 

The air conditioner cannot pass this cool, comfortable air to your house if the evaporator is frozen. 

Some common signs of a frozen evaporator are frost on the refrigerant tank, high bills, excessive condensate drainage, etc. 

The freezing mostly happens due to clogged air filters and drain lines.

Since accessing the evaporator coil is difficult, you need an HVAC team to fix the problem. 

5. Leaking refrigerant

The refrigerant fluid inside the copper coils helps absorb the heat from the air in the evaporator coil. 

The refrigerant tank in the air conditioner should have a specific amount of refrigerant fluid to work properly. 

If the refrigerant is low, the reason is leaking due to cracks, rust, or erosion. 

Leaking of the refrigerant fluid will badly affect your air conditioner and won’t let your room have enough cool air. 

When there is a leakage, it is very important to fix it. 

You can understand by a hissing sound coming out of the unit, and the energy bills will be very high.

You cannot fix it yourself. 

Consult a trained HVAC technician to replace or repair the refrigerant tank and refill the fluid. 

6. A bad or failing compressor

The role of the air conditioner’s compressor is to compress the refrigerant, raise its temperature and transport it to the outdoor coil. 

The procedure gathers heat from your house and releases it outside. 

The heat will not release outside if the compressor is at fault. 

Therefore, the air conditioner cannot cool down your room. 

Many people misdiagnose compressor failure. 

Some symptoms resemble compressor failure, and many other situations can cause the compressor to fail, making it difficult to identify. 

If you cannot confirm the problem but have a suspect, get a second opinion from the HVAC technician. 

Besides, the expert can fix the problem better.

7. Repair leaking ductwork

If the ductwork is very old, there could be a chance of leakage. 

A leaky duct will make the cool air escape, for which the air conditioner cannot cool down your house despite running. 

The ductwork must be sealed properly so that the cool air does not escape through the attic space. 

If your ductwork leaks, you need an air duct assessment to fix the problem. 

The team can inspect the ducts properly and replace the torn ducts. 

8. Undersized air conditioner

A small air conditioner will not make your house cool enough. 

The size of your room determines the size of the air conditioner. 

If you use an air conditioner smaller than your room, the unit will constantly struggle to make your room cool, but in vain. 

If the room is bigger, the cool air from the air conditioner won’t reach every corner of the room. 

It will keep struggling without ending the cycles, increasing your house’s energy bills. 

So, before you buy the unit, consider the house size. 

If you are naive, measure the room’s square footage and inform the HVAC company staff to help you. 

9. Bad or failing air conditioner capacitor

The outdoor fan will run, but the compressor may not. 

The reason is a bad or failing capacitor. 

The capacitors are like batteries. 

There are two of them – a start capacitor and a run capacitor. 

The capacitors power the motor in the compressor and the blower fan. 

If the capacitor is at fault, the compressor will not work well. 

As a result, your air conditioner won’t provide enough cool air in your room.

When the capacitor fails, the motor will make a humming noise.

You can identify the problem by hearing a clicking sound from your air conditioner. 

Replacing the capacitor is not your work. 

Call an HVAC team for help. 

10. Broken fan motor

Fan motors can wear and tear over time, especially if your air conditioner does not undergo regular maintenance.

Your air conditioner cannot provide enough cool air with a broken fan motor. 

You can identify the problem by hearing a buzzing sound from your air conditioner. 

Try to reset your unit by pressing the reset or overload button. 

Also, spin the fan blades clockwise. 

If it does not work well, the problem is with the fan motor. 

You need to replace the motor with the help of an HVAC team guide. 

11. Excessive ventilation in the room

The air conditioner works by dehumidifying the room where they are installed. 

The existing humid air is run through the evaporator to be chemically cooled and circulated. 

The process repeats until the room is properly cooled down and reaches the desired temperature you have set on the thermostat. 

If the rooms are not properly sealed, the cool air will escape from the open areas and won’t cool your room properly. 

So, while your air conditioner is operating, ensure that your room does not have excessive ventilation. 

12. Insufficient insulation

Some rooms of the house can be hotter than the rooms. 

In that case, the air conditioner may not cool the room properly. 

Have a look at the ductwork for insulation. 

Sometimes the insulated ducts also need exterior insulation. 

If the ducts are not properly insulated, they can heat the air too much after leaving the blower. 

If the ducts are uninsulated and your air conditioner is not cooling the room enough, consult an HVAC professional to make the insulation amendments. 

While checking for the vent insulation, hold your hands close to the joints to check for air leaks. 

13. Too many incandescent lights

Lights can heat your room to a great extent. 

If your room has too many lights, the room will be very hot. 

As a result, the air conditioner may not cool down your room properly. 

You must get rid of some lights and keep only the required number. 

You can also replace the incandescent lights with LED lights. 

They are more efficient, emit less heat, and save energy bills.

Sometimes, the rooms have windows exposed to excessive direct sunlight will also make the room hotter. 

Close the windows when your unit functions. 

14. The air conditioner is still not cooling.

When your air conditioner does not cool your room despite running profusely, try finding out what is wrong with the above-discussed points. 

You may not be able to fix them, but you can confirm it. 

If you cross-check with the above problems and have done everything you can, we recommend you contact the HVAC expert to help you out. 

If you want your air conditioner to run efficiently, you must maintain regular unit maintenance. 

Regular maintenance by the HVAC team will let you know what is wrong with your air conditioner and whether any part of the unit requires repair or replacement. 

This way, you can avoid problems. 

15. Damaged heat pump

Sometimes, the outdoor unit of your house could be a heat pump. 

The heat pump resembles an air conditioner unit but has different parts that help cool and heat your room. 

The system works like an air conditioner’s condenser unit during cooling operations. 

So, it can have the same issues, like dirty air filters and coils, refrigerant leaks, etc. 

Check the thermostat settings, air filters, and condenser unit if the heat pump does not cool your room. 

Call the local HVAC dealer to fix the problem.

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Final thoughts

An air conditioner is needed to cool down your room. 

But if the unit fails in the one thing it is supposed to do, something is very wrong. 

Some common reasons are clogged air filters and coils, frozen evaporator coils, failed capacitors and compressors, leaking refrigerant, small units, too much light, and ventilation, etc. 

Since there are so many reasons, you need an HVAC expert to identify the real cause. 

You can confirm and fix some problems yourself, like the clogged air filters and outdoor condensers. 

Others will need professional guidance. 

Regular maintenance and servicing can prevent problems to some extent and keep your air conditioner efficient. 

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Arthur Smith

Howdy! I am Arthur Smith, an electrical engineer who is extremely passionate about electronics. I have lived in different parts of the US and currently reside in Wisconsin. I am one of those rare children who knew what he wanted to study and do in life right from the start. I was a curious child who wanted to know how switches work and how the AC works, and I would always observe my dad whenever he would handle the wires and fix things around the house. I currently work as an electrical engineer at a reputed company and write for this blog. And I read loads of books or play video games in my free time.

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