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Hometown Heating and Air Conditioning Blog

Buzz, Bang, or Boom: AC Sounds You Don’t Want to Hear


Let’s face it–no air conditioner is ever going to operate in complete silence. There have been a lot of technological advancements that help certain cooling systems function much more quietly, such as inverter drive and variable speed AC systems. But for the most part, you’re always going to hear your outdoor compressor cycling on and off, and you’ll hear the whoosh of air through your vents, plus perhaps even the flexing of your ductwork as temperatures fluctuate.

What you shouldn’t hear, however, is banging, buzzing, booming, or any other noise you’re unfamiliar with. Strange noises aren’t something to be ignored. Neglecting them can only cause problems to grow, until you’re left scrambling to buy a new air conditioner in the middle of summer because yours has completely broken down.

Read on as we uncover what these, and more, sounds mean and why they’re so ominous.


Why exactly shouldn’t you hear buzzing coming from your air conditioner? Well, because this usually signals an electrical problem. Not only can an electrical issue lead to the breakdown of your air conditioner, but it also poses a safety hazard.

In the best-case scenario, your system’s circuit breaker will trip and shut the AC off if this were to occur, but you shouldn’t rely on this! If you hear buzzing, please shut off your air conditioner and call our team for an inspection.


This is typically the sign that something has become loose. The good news is this usually isn’t a severe problem. In fact, it may be the result of natural wear and tear. Perhaps a fan belt broke in your aging air conditioner.

When it becomes severe is when homeowners wait too long to have this problem checked out and repaired. Letting your AC continue to run with a loose or failing component reduces efficiency and increases the chance of a premature breakdown.


When your air conditioner starts up, does it sound like it’s booming instead of simply cycling on? This is called hard-starting and could very well indicate a problem with your compressor. The compressor is the heart of your air conditioning system, so this isn’t something you want to delay repairing.

Hissing or Bubbling

These two sounds both indicate the same potential problem–a refrigerant leak! The refrigerant in your air conditioner was charged during manufacturing, and it’s in a closed-loop system. This means that refrigerant should last the entire lifespan of your air conditioner. Refrigerant leaks are harmful to the compressor and can lead to a total system breakdown.

During your cooling system’s operation, refrigerant shifts from liquid to gas and back in order to remove heat from your home and provide chilled air instead. Depending on where the leak is occurring in this process, you’ll either hear the bubbling of liquid refrigerant or hissing of gas refrigerant.


Rattling is one of those noises that can indicate something really minor, such as a loose panel on the condenser cabinet, or perhaps even a loose joint in your ductwork. Still though, even though these are minor, they can turn into big problems if not dealt with.

Don’t let strange AC sounds turn into something worse! Contact Hometown Heating and Air Conditioning today for reliable Concord AC repairs.

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