AC Buzzing Every Few Minutes (Danger? Actionable Tips)

It can be frustrating when your AC starts making concerning noises on a hot summer’s day. Hearing a buzzing sound will have you questioning what is wrong with the AC. They get put to work during those heat spells, but they can eventually experience wear and tear after prolonged use. 

It may worry you to hear odd noises from your AC, but it is usually an easy fix before enjoying cool air once again.  

Physical damage, mechanical failure, and wear and tear can prevent an AC from working properly. When something isn’t running as it should it can cause buzzing noises. AC units should undergo maintenance regularly by a professional to ensure it is running efficiently. Allowing strange noises to go unchecked can not only damage your AC, but endanger yourself and your family.

Is It Dangerous to Leave My AC On if It’s Buzzing?

An air conditioner should not be left on if it is making buzzing noises. You may still have cool air circulating perfectly through your home even though it is making unusual sounds. Although it seems to be working fine, it should not be used if it is making prolonged buzzing noises.

If it is continued to be run and there is a loose or broken piece, this can damage your entire unit. It can also cost you more down the road if more pieces become involved. Using the buzzing AC could potentially put you and your family in danger if it is an electrical issue. 

The sound could be caused by electric arcing, which is the jump of electricity from one connection to the next. If the difference between the two points are too high, it could cause sparking. This could jeopardize the safety of your home, such as causing a fire. When you hear buzzing come from your AC, it is best to turn this off immediately. 

Once it is off, a professional air conditioning person should be contacted to take a look. They will inspect the unit to check for potential electrical hazards and fix the source of the buzzing. Later in this article, we will outline possible causes of your unit noises. 

What Is Causing My AC to Buzz Every Few Minutes?

Buzzing could signal multiple different problems, such as compromised electrical, loose bolts, or a faulty compressor. This is a normal noise made by most ACs, making it difficult to find the exact root cause. Read on to discover the most frequent known causes of an AC unit to buzz every few minutes. 

Loose Bolts or Panels 

Various components within the unit could be causing the buzzing or humming noise. While the AC is running, it can cause loose bolts or panels to vibrate, creating the buzzing noise. This can be determined if you push the panels in and the buzzing stops.

Thankfully, this is a problem with an easy solution. The bolts or panel can be tightened with a screwdriver once the power to the AC has been shut off. If bolts are missing, they can be replaced with ones from a hardware store. 

When the bolts and panels are not secure, this can cause lower efficiency of your AC.

Bad or Failing Contactor 

The contactor is used to control the high and low voltage within the AC. It has a coil that closes when energized that helps power up the unit. The coil can engage and disengage the thermostat by utilizing low voltage. The tips to the contactor can begin to wear down, causing them to stick and make a buzzing sound. 

Failing Contactor

The contactor can go bad entirely which also creates a buzzing noise. In this case, the only solution is to replace the contactor entirely. This piece has high voltage and should only be replaced by a professional. 

Capacitor Issues

When a capacitor begins to fail, it can start making a buzzing noise. In addition, a bad or broken capacitor can cause your AC to whistle or use more power than it should. The capacitor is what encourages the compressor to start and brings power to the fan, as well as the blower motor for the inside unit. If the capacitor begins to fail or go bad, this blocks the AC from starting and running. 

Capacitor Issues

If the capacitor has gone bad, it will not send ongoing power throughout the unit. It may send occasional power surges to the fan, causing buzzing noises in the indoor unit. This will also cause your AC to turn on and off unexpectedly, or not at all. 

Compressor going bad

For the fan to work properly in your AC, it requires the help of the compressor. If this is not working, cool air will not be circulated efficiently. When the compressor begins to wear down, it usually begins to make a buzzing noise to let you know it is failing. 


Your AC should undergo maintenance regularly, with the compressor being no exception. If you notice any issues with your circuit breaker, this could mean it is your compressor causing the lack of cool air. They typically last 12-15 years and should be replaced to keep your AC running smoothly. 

Condensing Fan Motor

The condensing fan motor can be found outside of the unit on the top. You will visibly see it spinning. Due to the location, it can easily build up dirt and debris over time. A noticeable noise will be detected if the motor is not running properly. 

Condensing Fan Motor

To test if it is the condensing fan motor causing the sound, turn off the AC and try to spin the fan manually. If it is difficult to spin, this usually means it is time for an update. This is a fairly simple piece to replace and can be done by non professionals. 

Reversing Valve

If your reversing valve is having difficulty switching between modes, this may mean the reversing valve is failing. It usually fails due to being stuck on one mode, having a defective coil, or internally leaking of the valve. This can be checked by tapping the valve gently to see if it becomes freed up from the current mode. 

Reversing Valve

Issues with the reversing valve usually means physical damage or mechanical failure and it will need to be removed and replaced. When the source of the buzzing is the reversing valve, it means removing refrigerant and soldering the new valve. This must always be performed by a professional. 

Frozen AC Unit

Experiencing refrigerant leaks can freeze parts inside of the AC. The reduction of pressure can cause water vapor to freeze on top of the surface of the coil. When pieces become frozen, the parts will begin to vibrate and work inefficiently. 

AC units also have an air filter that should be cleaned approximately every one to three months. Ice will begin to build up on the coil with uncirculated air. To troubleshoot, unplug the AC unit and allow it to thaw. 

If you notice the buzzing is consistent even after allowing the unit to thaw, a technician should be called immediately. 

Broken Isolation Foot

The isolation foot is a crucial part of the AC unit and is almost always found at the bottom of the unit. It is made of rubber and helps support the AC, specifically by holding the compressor in place. 

This rubber material can become broken or deteriorate over years of use. When this occurs, this allows the compressor to begin to tilt, making it uneven. Due to the imbalance, the compressor will become loose inside the unit and begin to buzz as it runs. 

The isolation foot can be evaluated by an AC technician for wear and tear and replaced if possible. 

Refrigerant Leak

A refrigerant leak can cause the internal components inside your AC to freeze as the freon leaks from the copper refrigerant lines. This causes a wide range of problems, including the persistent buzzing noise. To begin troubleshooting, you can turn off the power to the AC and give it a few hours to thaw. 

Refrigerant Leak

You can then try to seal the leak up by using a sealant or tape. If the leak is too large, it will have to be repaired by an AC technician. If the leak can be repaired, you can then add more freon to ensure smooth running. 

Fan Blades Unbalanced

Fade blades can become unbalanced when either of the two become bent, damage, or build up dirt. The cover can be removed to see if the fans are coming into contact with the cabinet, fan housing or insulation. If there are foreign objects, they should be removed. 

Ensure the fans are clean and not bent or warped. If there are no foreign objects and the fans are dirt free, the fans may be hitting excessive water. Water can become pooled if the drain port is blocked. Remove any obstructions from the drain port and follow previous recommendations to see if this causes fans to work in harmony. 

Is There a Way to Reduce the Buzzing Noise?

Buzzing noises can be reduced as long as there is not an issue with any components within the unit. Typically, the buzzing alerts you to possible issues or damage within your AC that need immediate attention. Once a professional inspects your system and deems it safe, you can then begin to find avenues to reduce the buzzing sound. 

As long as your AC is running smoothly, a sound blanket can be used. This blanket goes on the outside unit to help reduce the noise. If you have an indoor system, the air handler closet can be insulated to drown out unwanted sounds. 

Should I Repair or Replace My AC Unit?

If you have a relatively new AC unit, it is best to fix the part that is faulty. New systems do not typically have multiple problems occurring at once. Usually it is only one part that is out of sync with the rest and should be an easy fix by a professional.

AC units should be replaced every 10-15 years to ensure they are running at full capacity. If you find your AC having difficulty around the 10 year mark, it would be worth it to replace the system altogether. Regardless if your AC is new or heading to the finish line, it should receive regular maintenance to ensure proper operation. 


Having your AC unit stop working is a common frustration that many homeowners have. After noticing your AC is making a loud noise, the first thing to be done is to find the problem. Finding the troublesome component allows you to have it checked and replaced.

Some pieces of the AC can be easily replaced and followed with DIY instructions. Other parts, such as the reversing valve, must be replaced by a professional. In some cases, the buzzing noise might be a sign that it is time to completely replace the existing system. 

Your AC unit should be changed every 10-15 years. If it is getting close to this time and you experience odd noises, it is the perfect time to indulge in a new unit.

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