Updated July 24, 2023

Even older cooling systems are relatively quiet. The newest models make little to no noise when they are operating. Therefore, when you start to hear noises coming from the unit while it is running in your Norcross, GA, home, it should catch your attention.

Odd noises are the first sign that something is wrong with the unit. If you can catch the problem early enough, you could save your system, which would also save you money. Our team from Bardi Heating, Cooling & Plumbing has been helping your neighbors maintain their cooling systems for more than 30 years now. We can do the same for you. Here are some noises that your AC may make and what they mean.


If you are hearing banging noises from your cooling system while it is running, this is not a good sign. Loose parts are often the culprit. Debris is another. In this situation, it is important to take a look inside to find the item that is making the banging noises. If it is just debris that found its way inside, the debris can simply be removed. Then, a professional like us will figure out if it caused any damage.

In more serious cases, it is a loose part. Many cooling systems have a simple, interior design, so it is easy to spot a component that is no longer in its place. Once it is found, a technician figures out how the situation occurred in the first place. He works to put the part back where it belongs. Then, he will run a series of tests to make sure that the unit is running as expected. A professional also determines if the loose piece is a sign of something else happening in the unit. It could be a sign that a larger or more important component is coming loose, too. During an inspection, a professional jots down his notes. Then, he will present them to you along with his recommendations.

When the noise is coming from the compressor, it could be a piston, rod, or crankshaft that became loose. The compressor is the heart of a cooling unit. In order for the AC to work at an optimal level, the compressor and all its various parts have to be in their places.


Clanking sounds are often the result of debris or a loose part. This is a similar situation to banging. It could just be a different component that makes a different sound. Since nothing should ever be loose inside a cooling unit, the situation is given the attention it requires by a professional.

When there is a clanking sound that is not the result of a loose part or the compressor, it could be the indoor blower or the outdoor fan blades. If they are clanking, it means that they are no longer balanced. The fans must be working as expected so that the output produced can reach its destination. Otherwise, you may notice that your energy costs are increasing and your rooms aren’t being cooled as required.


Slamming sounds are often caused by a loose part or debris. Slamming sounds can also be caused when you turn off the unit. If that is the case, the sound may be caused by a closing damper, the air filter hitting up against the return grille, or a blower motor fan issue. An AC unit has springs in the compressor. Those springs could simply be failing and no longer providing support. If you open the unit from inside the home or outside and you do not spot any debris or obvious loose parts, the next step is to have a professional take a look.

Bubbling or Gurgling

If you can hear bubbling or gurgling sounds coming from your cooling system, it could be due to the refrigerant leaking in your system. The condensate drain line could also be clogged. Leaks are bad because they could lead to corrosion on the coils. Clogs can lead to leaks, too, which is not optimal either. If the unit senses that there is a backup of liquid, it will stop working.


When you hear noises that resemble metal rubbing on metal and sound like screeching, this could be due to the fan motor. Essentially, it is worn-out, so it is struggling to spin and operate as intended. If the fan motor is truly screeching, it means that a replacement is on the horizon.


Squealing sounds are usually fan-related, too. Instead of the motor, they are often due to the belt. If the squealing is constant or intermittent, the sound is a sign that the fan belt is worn out. At this point, it needs to be replaced. If it is allowed to keep running, it will tear, which will cause the cooling unit to stop working altogether. So, if you spot it soon enough, at least you will not be left without a working AC longer than necessary. You have time to schedule an appointment instead of calling in to request emergency service.


Buzzing sounds from a cooling unit that is on often indicate that an electrical issue is occurring. A faulty relay switch, circuit breaker, or condenser fan motor could all be the culprit. For electrical issues, you are encouraged to call in a professional. If it is a faulty circuit breaker, you do not want to worsen the problem. In the worst-case scenario, you could knock out all the power to your home.


Clicking sounds from an operating cooling system are normal. When the AC switches from the fan to the compressor, a clicking sound is made. Then, when the compressor turns off and the unit switches back to the fan, it clicks again.

An indication that the clicking sound is not a good sign is when the unit is no longer producing cold air. The clicking could then be due to debris obstructing the fan. It could also be due to an electrical problem. If the culprit is debris, you can take a look at the fan located on the outside portion of the unit. When the unit is off, take a look and see if you can spot the debris. If you do not see anything suspicious, the sounds could be due to the thermostat, compressor, or capacitor. Since these three parts are tied to the electricity function of the AC, you are encouraged to have a professional take a look. While you can try peeking around, you risk making the problem worse.


Humming is a sign that there is an electrical issue occurring with your cooling system. Humming sounds are often caused by loose wires or hardware as well as blower motor issues. When it comes to electrical issues, it is best to have a professional inspect the situation.


If you hear whistling, it could be due to a dirty air filter, blocked return vent, or leaky ducts.

We can help alleviate the odd noises coming from your cooling system; just give us a call at Bardi Heating, Cooling & Plumbing in Norcross to schedule an appointment. We also provide heating and cooling services such as repairs, installations, and replacements as well as ongoing maintenance for all types of heating and cooling systems. We can also be of assistance with your indoor air quality needs. We look forward to showing you all the ways we can be of service to you.

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