Summertime means warm weather and a working air conditioning system is essential for staying cool and comfortable. But what happens when you turn on your AC, and the compressor runs, yet it still fails to cool? It can be very frustrating and confusing to know what to do next. In this article, we’ll explore possible causes of an AC compressor running but not cooling, and provide solutions to help you beat the heat this summer.

1. Introduction: Understanding the AC Compressor and Its Importance

If you own an air conditioning system, the compressor is the most important component. It is responsible for compressing and circulating the refrigerant required for cooling your home. Without the compressor, your AC system won’t function correctly.

The compressor has a significant role in cooling your home, which is why it’s important to understand its basic workflow and functions. The refrigerant reaches the compressor in its low-pressure gaseous state and compresses it to transform it into a high-pressure gas. This high-pressure gas passes through the condenser coil, which helps expel the heat outdoors, and finally, the cooled refrigerant enters the evaporator coil to cool your home.

Although the compressor is essential, it’s not immune to wear and tear, which can cause various problems. In this article, we will discuss the common reasons why an AC compressor runs but doesn’t cool. We will also provide solutions to fix these issues. Keep reading to learn more!

2. Common Reasons why AC Compressor Runs but doesn’t Cool

When an AC compressor is running but still fails to cool your room, there could be several reasons why it’s not working properly. Here are some common causes of this issue:

Low Refrigerant Levels

One of the most common reasons why an AC compressor runs but doesn’t cool is due to low refrigerant levels. A refrigerant is a key component of your air conditioning system that cools the air inside your home. When refrigerant levels are low, your AC has to work harder to cool your home, resulting in insufficient cooling. To diagnose this issue, you can use a refrigerant pressure gauge to check the pressure levels in the system. If the pressure is below the recommended level, then you should refill the refrigerant. However, it’s crucial to note that refilling refrigerant is a job for professionals, and you should avoid doing it yourself.

Faulty Capacitor

Another reason why your AC compressor may run but not cool is due to a faulty capacitor. A capacitor is an electrical component that powers the compressor to cool the air. If the capacitor is defective, the compressor won’t receive enough power to function, leading to poor cooling performance. You can check the capacitor using a multimeter for continuity. If it’s faulty, you should replace it with a new one.

Dirty Condenser Coil

A dirty condenser coil can also lead to an AC compressor running without providing adequate cooling. The condenser coil helps to release the hot air outside, and if it’s covered with dirt and debris, it will prevent the hot air from being released, which will result in poor cooling. To clean the condenser coil, you can use a soft-bristled brush or a cleaning solution to get rid of the dirt and debris. However, if you’re not comfortable doing it yourself, you can seek professional help.

By understanding these common reasons why your AC compressor is running but not cooling, you’ll be able to troubleshoot and fix the issue before it becomes a more significant problem.

3. Low Refrigerant Levels: How to Diagnose and Fix the Issue

Can an AC Compressor Running But Not Cooling?

When an AC compressor runs but doesn’t cool, the problem can often be traced back to low refrigerant levels. Refrigerant is the lifeblood of your air conditioning system, and without it, your AC will struggle to regulate temperature and maintain proper cooling.

To diagnose low refrigerant levels, you’ll need to look for certain signs and symptoms. For instance, if you notice weak airflow from your AC, warm air coming from the vents, or excessive condensation around the evaporator coils, these could be telltale signs of low refrigerant levels.

Fortunately, fixing low refrigerant levels is a relatively straightforward process for most homeowners. You’ll need to locate the refrigerant line that feeds into your compressor and use a gauge to determine what the pressure levels are like. If they’re low, it’s likely because you have a leak somewhere in the system.

To repair the leak, you’ll need to identify where it’s coming from and then fix it by replacing worn-out seals, valves, or pipes. Once the leak is repaired, you can then recharge your system with fresh refrigerant and get your AC up and running again in no time.

Remember, working with refrigerant can be dangerous, so it’s always advisable to seek the help of a professional if you don’t feel comfortable doing it yourself. They can help you locate and fix leaks, as well as recharge your system with new refrigerant to restore proper cooling.

4. Faulty Capacitor: Causes and Methods of Replacement

If your AC compressor is running but not cooling, one possible cause could be a faulty capacitor. The capacitor is responsible for starting the compressor and if it is not functioning properly, then the compressor will struggle to start.

There are a few reasons why a capacitor can become faulty, including age, extreme weather conditions, or voltage issues. If you suspect that your capacitor is the culprit, it is best to call an HVAC professional to diagnose the issue and perform the necessary repairs.

Replacing a faulty capacitor is a relatively straightforward process but should only be done by a professional. They will first turn off the power to the unit and then discharge any stored electricity in the capacitor to prevent injury. The old capacitor will then be removed, and a new one will be installed and secured in its place.

It is important to note that installing the wrong type of capacitor can cause irreparable damage to your compressor. Therefore, it is essential to hire an experienced technician who can accurately diagnose the issue and use the correct replacement capacitor. Investing in professional repairs can save you time and money in the long run and ensure that your AC compressor runs efficiently.

5. Dirty Condenser Coil: Cleaning Techniques for Improved Cooling

One common reason why an AC compressor may run but not cool is a dirty condenser coil. Over time, dust, dirt, and debris can accumulate on the outside fins of the condenser coil, reducing its ability to release heat and causing the compressor to work harder. Fortunately, this is a relatively easy problem to diagnose and fix with some simple cleaning techniques.

Diagnosing a Dirty Condenser Coil

To diagnose a dirty condenser coil, you can simply examine the unit on the outside of your home or business and look for any visible signs of buildup or blockages. A dirty coil may appear dusty, discolored, or have small debris particles stuck to the fins. You can also check the airflow coming out of the unit to see if it feels weaker than normal.

Cleaning Techniques

To clean the condenser coil, you will need a few basic tools and supplies. First, turn off the power to the unit to avoid any potential electrical hazards. Next, use a soft-bristle brush or vacuum attachment to gently remove any loose dirt or debris. Be careful not to damage the fins of the coil, as this can affect its effectiveness.

If the coil is heavily clogged with dirt, you may need to use a specialized coil cleaner solution and rinse it off with a hose. Make sure to follow the manufacturer’s instructions carefully and wear appropriate protective gear during the cleaning process.

Benefits of a Clean Condenser Coil

Cleaning the condenser coil can result in several benefits, including improved cooling efficiency, reduced energy consumption, and longer lifespan of the compressor. By keeping the coil clean, the compressor can operate at a more optimal level, reducing the strain on the system and potentially preventing more costly repairs down the line.

Note: If you are uncomfortable performing any of these cleaning techniques or suspect that there may be additional issues affecting your AC compressor, it is best to seek help from a professional HVAC technician.

6. Malfunctioning Fan Motor: Replacing Defective Parts for Better Performance

If your AC compressor is running but not cooling, a malfunctioning fan motor could be the root cause. The fan motor plays a crucial role in the air conditioning process by drawing warm air from inside your home and expelling it outside through the condenser coil where it can be cooled down. If the fan motor fails to function properly, the compressor will keep running, but your AC won’t cool effectively.

Diagnosing a Faulty Fan Motor

If you suspect that your AC’s fan motor is the issue, switch off your system immediately and remove the access panel to check whether the blades are moving properly or not. If there is no movement in the blades, it means that your fan motor is not functioning correctly.

Typically, the most common cause of fan motor failure is age. If your fan motor is relatively old, it can get weak, making it challenging to spin the blades. Another reason why your fan motor might not be working could be due to faulty windings in the motor. In this case, a professional technician would need to repair or replace the windings to get it working.

Replacing Defective Parts

In some cases, a malfunctioning fan motor could be fixed by replacing defective parts. If your motor uses a capacitor, a weak or failed capacitor can result in reduced power to the motor, causing it to stop running. You can check the capacitor using a multimeter to see whether it is still working or not. If it is defective, then replace it with a new one.

Another part that could be causing the fan motor to malfunction is the contactor. A contactor is essentially a switch that turns off and on the motor. Over time, contactors can become worn, resulting in poor performance or even total failure. To fix this issue, a replacement contactor can be installed.

In conclusion, a malfunctioning fan motor can be a significant problem when it comes to your AC’s performance. However, with proper maintenance, regular cleaning, and timely replacement of defective parts, you can keep your AC running efficiently and effectively. If you are not sure about how to handle a faulty fan motor, always seek professional help from a trained technician.

7. Seeking Professional Help: When to Call an Expert for AC Compressor Issues?

Can an AC Compressor Running but Not Cooling? Seek Help from an Expert:

When to Call for Professional Assistance?

In most cases, AC compressor issues can be resolved by troubleshooting common problems such as low refrigerant levels, dirty condenser coils, and faulty capacitors. However, there are times when calling for professional help is necessary, especially when these issues persist despite DIY attempts to fix them.

Here are some situations when seeking help from an expert is the best option:

  • When your air conditioner is relatively new but still under warranty, it’s best to contact the manufacturer or an authorized service center for repairs rather than attempting to fix it yourself
  • When the problem is something that you have no experience or training in handling, such as a failed compressor pump or a refrigerant leak, it’s best to leave the job to professionals
  • When DIY repairs have not fixed the problem or have actually made the situation worse, calling for professional help is crucial
  • When you’re dealing with complex issues that require specialized tools and knowledge, such as electrical or mechanical problems, it’s better to seek help from trained technicians who have the skills and experience to solve these issues safely and effectively

The Importance of Choosing the Right Expert

When seeking professional help for your AC compressor issues, it’s important to choose the right expert who can provide you with reliable and effective solutions. Look for licensed and insured HVAC technicians who have a track record of delivering quality service and who are willing to provide you with references and reviews from previous clients.

You also want to make sure that the expert you hire offers a warranty or guarantee for the work they do, and that they are transparent about their pricing and service fees to avoid surprises. Lastly, consider the technician’s availability and responsiveness in case of emergencies and after-service support.

By taking the time to choose the right expert and knowing when to seek professional assistance, you can ensure that your AC compressor runs smoothly and efficiently, keeping you cool and comfortable during hot weather.

People Also Ask

Why is my AC compressor running but not cooling?

There could be various reasons why your AC compressor is running but not cooling. Some common reasons include dirty air filters, refrigerant leaks, broken or malfunctioning compressor, or a faulty thermostat.

How can I fix my AC compressor not cooling?

Fixing an AC compressor that is not cooling requires identifying and addressing the underlying issue. This could involve cleaning or replacing air filters, adding refrigerant, repairing or replacing the compressor, or replacing the thermostat.

What are the signs of a bad AC compressor?

Signs of a bad AC compressor include warm air blowing from the AC, strange noises coming from the unit, higher electricity bills, and visible signs of leakage or damage. If you notice any of these signs, it is recommended to seek professional repair services.

Can a weak capacitor cause AC not cooling?

Yes, a weak capacitor can cause your AC system to malfunction and not cool properly. The capacitor is responsible for providing the extra electrical power needed to start the compressor and keep it running consistently.

What should I do if my AC compressor is not cooling?

If your AC compressor is not cooling, the first step is to identify the underlying issue. Check your air filters, thermostat settings, and circuit breakers to ensure everything is functioning properly. If these are not the cause, it is recommended to seek professional repair services.


There can be a range of issues causing an AC compressor to run but not cool. From replacing dirty air filters to repairing broken compressors, identifying the issue is crucial to restoring your AC function. Seeking professional repair services can ensure a proper assessment and resolution of the issue.