The Most Common Reasons for AC Not Cooling

What could be worse on a summer day than your air conditioner not cooling? This is the least we can expect to happen!

There are many reasons behind your AC not cooling the room properly. They can sound alarming to you, but you do not have to panic. Not all these causes are technical faults; some of them are non-technical as well, which can be fixed by yourself.

Read on to understand the reasons and how to fix your AC.

Common Reasons Why Your AC is not Cooling and their Solutions

Just because your air conditioning system is not cooling, it doesn’t necessarily mean you need an expensive repair or replace the unit altogether. Let us discuss below the major reasons why your AC unit is blowing hot air instead of cool air:

1. Clogged Air Filter

Clogged Air Filter

When dirt, dust, or other airborne particles congest the air filter, it affects the AC operation. The scrap accumulated in the filter blocks the airflow, thereby, reducing the cooling capacity of the air conditioner. It also hampers the circulation of cool air inside the room. In extreme cases, this might even lead to the shutdown of the AC system.


It is highly advisable to check the AC filter regularly to prevent such unwanted incidents. If needed, change the clogged filter and replace it with a new one.

2. Dirty Condenser Coils

Dirty Condenser Coils

If the air conditioner is not functioning properly, then the dirty condenser coils could be another reason. We all know that a condenser is an outdoor component. Dirt, grime, debris, and grass can get accumulated between the coil fins, clogging it. In every unit, the condenser dissipates heat, and to perform this task the condenser coils must be clean and free from any congestion.

Dirty condenser coils make the air conditioner less efficient, further making it harder for the unit to cool the room.


The only solution to this problem is to get a thorough cleaning done frequently by an expert technician.

3. Insufficient Coolant

Inadequate coolant or refrigerant is another contributor to your AC not cooling. The refrigerant circulates through the evaporator coils and lowers the temperature. It keeps the external heat at bay, thereby allowing cool air to come out of the interior vents of the unit. This makes your room cool down.

When your air conditioner is low on coolant, it cannot absorb much heat from the indoor air and then dump it outside. It may seem that your AC unit is running continuously but not cooling your room.


If you notice that your AC has low refrigerant, immediately call for a professional to refill the coolant.

There are primarily two reasons for a decrease in the refrigerant levels in your cooling system. The first one is the coolant leakage problem, which is quite easy to identify. Any noises like hissing or bubbling and ice build-up on the outside unit are clear indications that there is a loss of coolant in our AC.

Secondly, the coolant levels got decreased because of usage over time.

4. Faulty Compressor

If your AC unit is blowing hot hair instead of cool air even after your compressor is working, it is a key indicator that your compressor is defective. The job of a compressor is to compress the refrigerant and circulate the same through the evaporator and condenser coils. A faulty compressor does not initiate the cooling cycle and fails to pump the coolant through the system.


Do not try to fix this problem on your own. A damaged compressor needs replacement. Hence, get assistance from a professional AC repair technician.

5. Thermostat Issues

If your air conditioner runs non-stop, yet your room seems to be warmer, or if you experience a cooling system failure, then your thermostat is to blame. The thermostat is one of the most crucial parts of an air conditioning system, which senses the room temperature and then, allows the cooling system to function as per the user requirement.

Inconsistent or improper cooling of ACs are signs of thermostat malfunctioning. If your thermostat has a blank or unlighted display, it indicates a failure of the device which could be a result of dead batteries.


Since most thermostats rely on batteries for operation, it is better to change the batteries in them. Now recheck the function of your unit. If this does not seem to solve the problem, call a technician to fix it.

6. Incorrect Thermostat Setting

ac thermostat settings

If you notice any discrepancy in the temperature, the obvious thing that one needs to do is check for the thermostat settings. Make sure that it is set to provide cooling as required. Also, ensure that the pre-set points (ON, Constant Fan, or Heat) are correct.


If you feel that your cooling system is not working as expected even after running, change the settings. If you notice the thermostat settings as ON mode, change it back to Auto mode.

7. Tripped Circuit Breaker

When you are experiencing a cooling problem in your air conditioner, it could be because your unit is tripping your circuit breaker. If the outside unit breaker trips, the indoor unit continues to blow air into your home, which will be warm.


The only way to fix this is to check the breaker box and see if the breaker of the outdoor unit tripped. If yes, switch it on. After switching on, if it still trips, do not try to reset it. The best option is to contact a professional to repair this technical issue.

8. Faulty Motors

Faulty Motors

If there is a motor failure, it can threaten your cooling because the outdoor unit cannot dissipate heat outside. 


To best handle, this problem, seek the help of a professional. You can utilize the services of Urban Company professionals.

9. Undersized AC

If you have an undersized AC at home, it may take too long to cool down your house. Most of the time, many users end up with an AC that is too small for their home, resulting in insufficient cooling. When it comes to buying a cooling system, most people tend to go with their budget rather than the size of their home. When having an AC unit that is too small may seem that your home is never cool enough.


Always buy an AC based on the requirement of the room and not on the budget. The AC size should be as per the room size.

The other parameters considered for purchasing the right size AC are the climatic conditions of the area where you reside, square footage, construction quality, insulation quality, and more.

10. High Atmospheric Temperature

Keeping your AC at an optimum temperature not only promotes the energy efficiency of the unit but also guarantees effective functioning. In any case, where the temperature goes beyond the stipulated temperature limit, it brings down the cooling efficiency of the air conditioner.


Always get your AC installed in a place where the surrounding temperature is low and where it does not face the direct sun. You can achieve this by having some plants around the AC or any other way that does not keep the place hot.

11. Faulty AC Remote

Consider this scenario wherein the AC remote is remote. In such a case, the remote control cannot send signals to the sensor of the AC system.


Try placing the remote control close to the unit and press the on button. Check the batteries and their polarity. Also, check for the remote control settings. If nothing seems to play the trick, replace your AC remote control.


I hope this article gave you insights into why your AC is not cooling. Remember that it is not always a technical glitch that leads to less cooling or an ineffective AC. There may be some common problems that can be impacting your cooling system performance and your comfort.

Please use the comments section below if you have any questions to ask or if you want to know more. We will get all your questions answered at the earliest.

One Response

  1. I’ve always had the feeling that a motor problem was the reason why our AC hasn’t been working well recently. It all started when I heard a noise similar to an accelerating car from that unit, and ever since then the cooling just hasn’t been as good. If that part has broken down entirely, then I’ll look for an HVAC expert in the area that can lend us a hand right away.

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