AC Unit Buzzing Every Few Minutes? Here’s What’s Behind It

AC Unit Buzzing Every Few Minutes

While air conditioners can be noisy (many homeowners are used to it), some sounds they produce just aren’t normal. For example, it’s common to notice an AC unit buzzing every few minutes.

Unfortunately, as with most other HVAC issues, finding the cause and the appropriate fix is rarely straightforward. 

Hence, you should always first try to pinpoint the exact cause that is contributing to the AC unit buzzing every few minutes before taking any further action.

Here are the usual suspects that could be behind the ‘’buzz’’.

1. Loose Panels 

If the AC buzzing every few minutes persists, chances are some of the components are not snug, so to speak. For instance, a bolt holding a panel that got a bit loose will most likely cause a continuous buzzing noise.

There is a simple test you can do, though. Press on the panels of an AC unit to see if the noise disappears. 

If it does, you found the main culprit behind the AC unit buzzing every few minutes. You can simply tighten the loose screws and the issue will go away. If some bolts fell out, you can buy new ones for a few bucks at any hardware store.

2. Bad Contactor 

The contactor is an important electrical component in your air conditioning system because it breaks and connects the power lines that travel through the load. It consists of two latching electrical contacts that function like a drawbridge. 

In other words, when these two contacts are connected, the power can flow freely through the unit.

The problem is, all electrical components wear down over time. They can corrode, deteriorate from constantly rubbing together, and so on. 

Once that happens, their conductivity decreases. The current might dissipate elsewhere and produce arcs (sparks of electric discharge). These can weld contracts together or cause short circuits.

One of the main symptoms can be the AC unit buzzing every few minutes. This happens because contacts become loose due to contactor issues, and once the unit starts vibrating, the loose components will shake, causing a droning sound.

Additionally, you should also look at the casing to see any charred areas caused by arcs and keep vigilant for the smell of burning.

Lastly, check if your unit can power off. Since contacts need to be separated to cut the power, your unit won’t be able to stop the flow of electricity if they are stuck in the closed position.

3. Failing Capacitor

The capacitor is a component that kickstarts the motor of your AC by sending in an electrical surge (similar to a car engine). 

Once it starts malfunctioning, it can create all kinds of symptoms – a common one being the AC unit buzzing every few minutes. You may also notice a strong humming sound when you power on your AC.

Along with those noises, a sign that the capacitor is failing is also a poor cooling performance coupled with a significant rise in your energy bills.

Finally, if your AC randomly shuts off and powers on by itself or you notice that it takes a while for the unit to turn on, you can almost confirm that your capacitor is failing with certainty.

So what can you do about it?

Sadly, nothing. Capacitors are dangerous so we don’t recommend you tinker with them on your own. Even if you kill the power to your AC, the capacitor will still hold a significant amount of electrical charge.

Your best (and only) course of action is to contact an experienced HVAC tech.

4. Reversing Valve

If you have a heat pump (a unit that cools and heats), one of its main parts is the reversing valve. This valve reverses the direction of the flow of the refrigerant, thus changing the cycle from cooling to heating. 

If you hear a buzzing sound even when your heat is off, it’s most likely not a serious issue. The solenoid valve always runs at low power, so it could just be happening due to a loose screw. 

However, it could also point to a severe problem such as a refrigerant leak or a power-related problem where the current is jumping between different circuits.

Troubleshooting a reversing valve is not easy, so we recommend calling an HVAC tech who can diagnose the issue properly. 

5. Failing Compressor

The compressor converts the refrigerant from a low-pressure liquid into a high-pressure gas, and vice versa. This means that the compressor is ultimately in charge of changing the temperature and cooling the air.

When this component ceases to function properly, you may notice a drop in the airflow. If you already swapped out the filter, it could be a sign of a compressor failure. 

Another dead giveaway is the warm air coming from the vents, along with the circuit breaker that’s constantly tripping. This happens because an overheating compressor draws more power than it’s supposed to trip the breaker in the process.

Lastly, an AC unit buzzing every few minutes or any other sounds like ticking, rattling, rumbling, or chattering are clear indications you should call a professional AC service company.

6. Problems With The Fan Motor

This component sends the air conditioner air into your home. Once the unit cools the air, the fan motor pushes it through the ducts into your vents.

A faulty fan motor will be quite noisy. You may notice an AC unit buzzing every few minutes, but you may also hear squealing noises. The fix is usually lubricating the bearings or swapping out the belt.

Nevertheless, loud banging is usually a sign of a more serious problem.

Regardless of the nature of the sound, you should contact a professional as soon as you notice anything similar to the symptoms of a failing compressor. 

When is The Right Time To Call a Professional?

An AC unit buzzing every few minutes doesn’t sound like a big deal to many people. In fact, in most cases, you’ll be able to cool your house just fine without fixing anything. Still, this is usually a short-term solution and you’re most likely causing long-term damage in the process. 

By avoiding addressing the issue at the onset of the buzzing sound, you’re making the repair even more expensive than it really needs to be. 

We recommend checking if you have a loose panel Once you rule this out, you should power off your unit and call a professional.

If you’re situated in southeastern Florida, you can’t go wrong with Aztil Air Conditioning. We offer 24/7 emergency AC services and have the necessary expertise and personnel to successfully find the source of the buzzing and make it go away – for good.

Call us now at +561-559-2205 so we can help you get rid of the buzz.