Why Is My Outside AC Unit Not Running But Inside Is?

air conditioner condenser unit depicting outside ac unit stopped working

Temperatures are beginning to rise, meaning that your air conditioning system will be working full-time to help you feel comfortable. However, some homeowners will find that their air conditioner isn’t working as expected. For example, a common issue is where the outside AC unit not running but inside is. This common problem is caused by several reasons. Read on to learn more about what you can do about it.

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Why Is My Outside AC Unit Not Running But Inside Is?

Cooling systems have indoor and outdoor units that work together to generate the desired results. If one unit is not working, the unit will not cool your house, regardless of how long you wait. You can determine whether or not the outdoor unit is running by using one of two methods:

  • No Sound Is Heard From The Condenser: Check to see if your condenser is producing any sound. Some units are designed to run quietly but will still generate a low hum. If you can’t hear anything, then the motor and compressor aren’t working properly.
  • Warm Air From The Indoor Air Handler: Place a hand near the air conditioner’s indoor unit. The outdoor unit isn’t working properly if you feel hot air blowing through it. The warm summer air is passing through the system, and the air conditioner isn’t cooling it.

Related Article: How Much Clearance Is Necessary Around an Outdoor AC Unit?

What Causes The Outdoor Air Conditioner Fan To Stop Working?


The outdoor unit has a large fan. Consequently, the outdoor unit may stop working because of fan failure. This means the blades are not moving even if other components of the outdoor unit work fine. This can occur even if you are diligent about air filter replacement and other maintenance tasks. Here are several causes for a fan that stops rotating:

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Deficient Power Supply To The Air Conditioner

Fan motors are powered by electricity. If there is insufficient power, they cannot spin. It can be a challenge to determine what the exact inhibitor is in different cases. An experienced HVAC professional can help make an accurate diagnosis.

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Contactor Problems

The contactor’s job is to control the fan motor. Any kind of failure will stop the blades from rotating. It isn’t recommended to try fixing it on your own. Air conditioner issues tend to worsen when left in the hands of an untrained individual. Call an HVAC professional immediately for a reliable solution.

Bad Air Conditioner Capacitors

Bad capacitors can cause the outdoor unit’s fan to fail. An air conditioner capacitor stores energy, much like a battery. This way, the blades are able to spin continuously. After heavy usage, they lose their ability to store energy. Power surges and high temperatures can also damage this component. Capacitor failure means the fan won’t receive the power it needs to spin.

You can check to see if this is what’s going on with your particular unit by sliding a long wooden stick through the fan grate. Use the stick to nudge the blades gently to get them spinning. If they start to spin, you may have a bad capacitor on your hands. The fan will eventually stop working once again. Call a professional right away.

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Burnt Out AC Unit Fan Motor

Motors can burn out when they experience too much stress. As time passes, they also suffer from wear and tear. Poorly maintained systems experience this quicker than those that receive regular maintenance. Regular air conditioner maintenance is essential so that problems are resolved early, and costly HVAC repairs are avoided.

Related Article: Why Is HVAC Airflow So Important For My Home?

Debris On The Axle

image of air conditioner compressor that requires hvac repair

An external force, like that from a stick, should be sufficient to make the blades rotate. Inspect the fan axle for debris to see if this is causing an issue. The motor’s bearing may have dirt build-up on it. Hire an HVAC professional to disassemble and clean all components so that it moves as they should.

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What If The Entire Outside Air Conditioning Unit Isn’t Functioning?

There are some cases where the outdoor unit stops working altogether. This calls for immediate professional assistance. A non-functioning air conditioner in the middle of the summer is a problem many homeowners don’t want to deal with. Therefore, act quickly to resolve it. Here are several of the possible reasons your system breaks down suddenly:

Related Article: Follow These Simple Tips To Improve Your Home’s Indoor Air Quality

Thermostat Settings

image of homeowner adjusting thermostat fan settings

First, check the basics before jumping to the worst-case scenarios. First, check the thermostat settings. A family member may have pushed the wrong buttons, setting the temperature too high. Try lowering the thermostat setting and check if that changes anything. The thermostat may not even be powered on. Change the batteries before trying to start it up again.

Related Article: Debunking the Myths: The Truth About Central Air Conditioners

Dirty Outside Compressor Unit

An outdoor unit that has become too dirty can cause the compressor to overheat. A thick layer of dust acts as insulation, preventing the heat from being released into the environment. The system will shut down if it can no longer tolerate high temperatures. Check the unit to see if it has gotten dirty. Switch off the power and disconnect the system before cleaning. The best option is to contact an experienced HVAC technician to clean the unit for you.

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Safety Switch Lock

Cooling systems are fitted with safety switches that automatically lock the outdoor unit when they sense danger. A reset will get the air conditioner to work again. Turn the system off from the thermostat or the breaker to reset it. Wait several minutes, and turn it on again to determine if it’s back to normal. Otherwise, you need to contact a professional to help with advanced troubleshooting.

Related Article: How Does An Air Conditioner Tune-Up Save Me Money? 

Tripped AC Circuit Breaker

A recent thunderstorm may have caused power surges and overloaded the circuit breakers. Check the circuit panel to see if the breakers have tripped. Switch them off before turning them on again. If your home is an older structure, there may be blown fuses in the fuse box. If so, change the fuses. Call an HVAC technician for a replacement if your air conditioner has a fuse at the shut-off box. The breakers may sometimes trip repeatedly despite trying to normalize the situation. There may be a deeper electrical problem that only a licensed electrician can fix.

Air Conditioner Compressor Failure

The compressor is the air conditioner’s most crucial component. It pumps the refrigerant throughout the system at the right pressure level. Compressor failure can result in the air conditioner losing its cooling abilities. A good indication that the compressor is failing is when the unit stutters or generates a loud sound when turning it on. The unit may stop turning on completely after some time. Repairing this will be expensive, and you may need to upgrade the whole system.

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A malfunctioning outdoor unit can be a confusing situation to be in. A quick check may help you determine the possible culprit and sometimes require minimal effort to bring it back to normal. However, the problem may also be too complicated for an untrained homeowner to resolve. Call an HVAC professional right away. They can find the cause and repair the problem. You can be sure that your air conditioner will run smoothly again once the experts are done. 

You should also schedule central air conditioner maintenance. This way, problems do not escalate into bigger ones, and you can enjoy high levels of comfort and efficiency.

Related Article: Overcharged AC: How To Spot & Solve The Problem

Call Townsend Energy For All Your HVAC Requirements

Townsend Energy offers exceptional heating and cooling services in Northeastern Massachusetts, Southern New Hampshire & Maine. Our team of professionally certified technicians specializes in top-quality HVAC services, including air conditioner maintenance, mini-split repairs, furnace installations, and many more. Each of our friendly techs has the right tools, experience, and knowledge to conduct accurate HVAC system services. 

Our company offers quality and affordable services. Our tune-up services can increase the comfort, energy efficiency, and indoor air quality in your home while reducing your cooling expenses. If you require an HVAC system repair or replacement, we can recommend the best solution while working within your budget. We guarantee all our work to ensure your satisfaction. Contact Townsend Energy today to schedule a service appointment and get a free, in-home estimate.

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