Why Is My AC Compressor Working But Not Cooling?

image of an air conditioner air vent depicting ac outdoor unit that is working but not cooling

It feels like nothing could be worse when it is sweltering hot and the air conditioner does not cool the way it is supposed to. Energy levels dip, sleep can be difficult, and discomfort is an unwelcome companion. A working air conditioner is a summer essential. When malfunctioning air conditioners run but don’t cool the air as they should, they still draw the same amount of energy or more. When this happens, it is time to call the experts. This article explains one of the most common problems with an AC system that occurs during the summer – the AC compressor working but not cooling.

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Why Does An Air Conditioner’s Compressor Work Without Cooling The Air?

An air conditioner is made up of many parts that are supposed to work together for cooling the area around you. When one part stops functioning well, it is not unusual for it to cause a chain reaction. It cannot be fixed without finding the original cause of the problem. You should do a careful and thorough observation to find where the problem began. If you do not have time to observe or simply have no idea how it works, then it is time to bring in a qualified HVAC professional. A certified HVAC technician will find the problem and offer real solutions. Here are the most common reasons for air conditioning compressor failure:

1. Thermostat Is Not Set Up Correctly

woman trying to adjust thermostat

You should not automatically assume your air conditioner is broken. The air conditioner may be functioning properly but the issue could be the thermostat setup. Check your thermostat. Perhaps the temperature is not set low enough. It is not unusual for other members of the household to adjust the settings when you are not around. Try setting the numbers to a lower temperature and then wait for a few minutes to see if the problem has been solved. If the air is cooling comfortably, you have fixed the issue and can sit back and enjoy the cool air.

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2. Air Filter Is Dirty

image of a dirty air conditioner filter causing a frozen ac unit

Air conditioning filters play an integral role in cleaning the air. The air flows through the filter, but allergens, pollutants, and dirt are caught so they do not recirculate into the air. The filter keeps the unit clean. Cooling system parts work better and longer when they are clean. The problem comes in when the filter gets so dirty that air cannot flow through it. Your air conditioner will try to work harder to cool, but an uncleaned or unchanged filter can keep the energy usage high and the cooling comfort low. If you check and change the filter on a regular basis, you will avoid a slew of HVAC issues. Furthermore, filters are inexpensive and easily installed.

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3. Air Conditioner’s Condenser May Be Blocked

Central air conditioning systems utilize condenser units that are placed outside the home. The condenser unit has a large coil which is composed of fins that are thin but placed closely together. When the AC condenser works the way it is supposed to, the fans pull outside air into the unit. The air passes the coil to cool the home. Because this equipment is outside, debris like dirt, grass, and leaves can get stuck in the fins and cause problems. Dirty air conditioner coils lead to lower energy efficiency and you will notice that registers do not blow cool air as they should.

Use a vacuum and a brush to clean the coil. If cleaning the coils does not solve the problem, get in touch with a qualified professional. Problems caused by dirty coils can be avoided by scheduling air conditioner tune-ups on a yearly basis. HVAC technicians will clean the system as part of the tune-up. This helps keep your air conditioning system running at full efficiency and lessens the risk of more serious issues.

4. Evaporator Coil On Your Air Conditioning System Is Frozen

frozen evaporator coil of heat pump

There is an evaporator coil on your indoor system. The warm air from inside flows through this evaporator coil and transfers the heat to the refrigerant. This lowers the amount of humidity inside your home. When evaporator coils freeze up, they cause trouble with the setup and the unit is unable to generate cooler air. Keep an eye out for frost build-up on the air conditioner refrigerant tubing. You may see a rise in your utility bills, too much condensate drainage, and a problem with cooling. If you are not experienced or do not have the proper tools, you should not try to fix the problem by yourself. This problem should be solved by a certified HVAC technician.

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5. Air Conditioner Refrigerant Is Leaking

hvac technician with an air conditioner refrigerant leak detector

The refrigerant in your cooling system streams from outside to inside and then flows back outside. When it is flowing, it changes from a liquid refrigerant to a gas. The temperature of the refrigerant and gas fluctuates in temperature when it takes the heat from inside and pushes it outside. The refrigerant is integral to the cooling of your home. There should be an adequate amount to keep it circulating. When a leak in the tubing occurs, the refrigerant in the cooling system is reduced. The result is an inability to keep your home cool.

When the leak isn’t fixed, it will put too much burden on the system and the compressor will fail. Be sure to ask your HVAC professional to check the levels of the refrigerant and add more to the system if it needs it. Refrigerant is always checked during a yearly inspection of your cooling system.

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6. Air Conditioning System Is Too Small

Air conditioning systems vary in the capacity to cool. If the air conditioning system is too small for your home, it will not be able to provide adequate cooling. The problem will be very obvious when summer temperatures soar and your cooling unit cannot keep up. Look at the back of the AC unit to see the rating. You may be able to determine how adequate the system should be. Experienced HVAC technicians can calculate the load. A thorough calculation should have been done by the HVAC company that originally installed the unit.


7. HVAC Ducts Are Leaking

The ducts are the part of the system that transports conditioned air throughout the rooms of your home. When leaks in the ducts occur, some rooms may not cool off while other rooms stay as cool as they should be. Cold air may come out too fast and warm air from warmer areas could get inside the HVAC ducts. In this case, the air coming out of your vents will be warm instead of cool. The temperature of the room goes higher instead of lowering as it should. It can be a difficult task to determine where air leaks are coming from and the typical homeowner will likely need some help. An air conditioning professional can find and seal the problem leaks.

8. Air Conditioner Has Dirty Or Blocked Registers

image of a dirty hvac air register

It is not unreasonable that registers get dirty. When they have not been cleaned for a while, the problem builds and air cannot get through to cool the home. Be sure to clean the registers on a regular basis to keep this from happening. Another common issue is that registers are blocked. Sometimes furniture is placed over registers or other items are mistakenly placed on them. Check to see if any registers are blocked and remove the items or rearrange the furniture. Frequent vacuuming around and inside the registers can be helpful, as can taking the registers off and washing them by hand.

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9. It Is Incredibly Hot Outside

The sun is at its hottest during the summer. If your cooling system is powerful enough, it will be able to take on the challenge of the heat and keep you cool. When it does not have enough power to combat the sun, it will have trouble cooling your home. Be sure that sunlight is not directly hitting the thermostat. If it is, the sensor will believe the room is warmer than it actually is. Your system will work even harder to cool your home. It will stress the air conditioner and your system may become unstable. You can keep this from happening by closing curtains or shades during the day. This keeps the thermostat cooler and eases stress on your air conditioning unit.

10. Lack Of Proper Air Conditioner Maintenance

air conditioner maintenance

In order for a cooling system to function at its best, it needs consistent care and maintenance. Homeowners can take care of simple things, such as cleaning registers and changing filters, but other air conditioner maintenance should be taken care of by professionals that have been certified in HVAC systems. It is wise to schedule one or two tune-ups every year. The technician is better able to find possible problems and keep them from becoming even bigger. A good tech can keep your system running smoothly so you do not have to deal with bigger, more expensive problems in the future.

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11. Exterior Air Conditioner Fan Motor Has Issues

The fan motor in your system’s outside unit pushes heat out and away from your house. When the fan stops working the way it should, an overheated compressor can cause the entire system to turn off in order to keep more damage from occurring. HVAC technicians can fix the problem and keep it from getting worse.


Nobody wants to be too warm inside their own house. A well-functioning air conditioner can keep you cool and comfortable. HVAC professionals can fix problems and help prevent them.

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Lawes Company provides advanced heating and cooling services for residents of Monmouth and Ocean Counties, New Jersey. By working with us, you are assured of a certified technician who is able to provide excellence in HVAC tune-ups, timely repairs, professional installation, and more. All of our techs have the knowledge as well as the experience to service HVAC systems correctly.

Lawes Company guarantees competitive heating and cooling costs. Our maintenance service is sure to improve your comfort, increase energy efficiency and reduce home heating and cooling expense. If you need an HVAC repair or a replacement system, let us recommend the best solution for your home while working within your budget. Our company backs our work with a guarantee to ensure your satisfaction. If you are ready to schedule an appointment, just pick up your phone and give Lawes Company a call. Ask us about our free, in-home estimates.

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