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RKM Heating and Air Conditioning Blog

Sounds You Do Want to Hear Come from Your AC

Unusual sounds coming from your air conditioner are usually easy to identify. They’re loud and surprisingly most of the time, but they can also be quiet and barely noticeable. These sounds are the ones that mix in with your regular AC sounds that are perfectly normal to hear. In fact, sometimes it’s about when you hear a particular sound that makes it OK or not OK to hear.

That’s why it’s so important for homeowners to understand how your air conditioner works so they can easily identify when something is wrong. One of the best ways to understand your AC unit is to know what sounds are common to hear throughout the day. Then, you know when you need to call for air conditioning service in Irvine, CA.

Common Air Conditioner Sounds

Compressor Humming

When your air conditioner begins to cool your home, you’ll hear the compressor hum from inside its cabinet. This humming sound means that air is being cooled to circulate through your home and lower the temperature. Your compressor knows when to turn on because your thermostat reads the temperature inside your home.

When it begins to get too hot, the thermostat sends a signal to your HVAC unit to turn on the compressor motor to pressurize refrigerant for cooling. When you hear the hum of your compressor kick on, you should begin to feel cool air blowing from your vents a short time later. If you don’t feel cool air, something may be wrong with your unit. 

Fan Blowing

While your AC unit is working to cool your home, you may also hear the gentle sound of air blowing as fan blades turn. Like the hum of the compressor, this sound should be slow and steady. It may even become white noise that fades into the background noise that you don’t even notice unless you think about it. 

Water Movement

When your air conditioner cools air, moisture condensates and has to drain out through the coils outside of your home. It’s normal to hear water running occasionally through the cooling process. Keep in mind that if you hear water that sounds like it’s coming from a faucet, or water that isn’t turning off, something may be wrong. 

Ductwork Rattling

The ductwork that connects to your central indoor cabinet is made of thin metal. The material expands and contracts with temperature changes. You may hear the ductwork rattle as it changes shape. This is completely normal to hear once in a while. If you begin to hear ductwork rattling all the time, something may be loose.


As your AC unit cycles down from cooling your home, it may click. It’s normal when your compressor and motor slow down to stop after running. But if you hear clicking at other times, a part inside your unit may be loose or your compressor or motor are having problems.

When in doubt, it’s always a good idea to give us a call. You can describe the sound as well as what your AC unit was doing when you heard it, and we can decide whether or not you have a reason to be concerned. If there is something wrong, we can come out and assess the problem and offer a solution.

Contact RKM Heating and Air Conditioning today to schedule an appointment with us. Done Right, Priced Right.

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