AC System Noises: What Is Normal and What Is Not

Hearing strange or loud noises from your AC system can alarm any homeowner. But not all noise is bad noise. Your air conditioner will make various noises before, during, and even after cooling your home. Understanding your AC’s sounds will give you peace of mind, knowing what is normal and what is not. 

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Normal AC System Noises

It’s important to remember that an AC system will make some noises while operating and possibly even when not. This is not always a cause for concern. In fact, it’s often just your system doing what it was designed to do, and the sounds it makes can be perfectly normal. 

Startup Sounds

When your AC system starts up, it may sound like a tiny airplane preparing to take off. This is normal and is due to the simultaneous start of your system’s many moving parts. The initial noise should dissipate after a few seconds and the system gets going. However, this sound may return again during a new cooling cycle. 

Clicking Noises

After your AC system completes its cooling cycle, it is normal for it to make a series of clicking sounds. This just means that your system is coming to a stop. If the clicking is constant, however, it may be an indication of an object stuck in the fan assembly or an issue with your thermostat. 

Blowing Sounds

As your system moves air through your home’s ducts and vents, you may hear a low, steady blowing sound. This is another normal noise for your AC to make. However, if you hear humming or buzzing noises, these might be signs of an electrical issue or loose parts in your system. 

Noisy AC

Even if your AC system is perfectly fine, its noises may be more than a little annoying for some. If so, homeowners can consider upgrading their system to a more efficient and quieter unit. A newer, more efficient system not only reduces noise but also saves energy and lowers your utility bills. You could also hire an HVAC professional to install a sound blanket or quiet fence to help with the noise. These enclosures physically block noise and absorb it with multiple layers of insulating fabric.

Time To Call The Professionals

When your system is running fine, you may not hear much noise. But if something is wrong with it, it will make a few sounds to signal this to you. If you hear an abnormal or alarming sound coming from your unit, it’s crucial that you contact a professional for a proper diagnosis. This will ensure that any issues are identified and resolved correctly, giving you peace of mind about your AC system’s performance. 

Banging or Rattling 

A banging sound coming from your unit could indicate that there are loose internal parts such as screws, springs, or bolts. An issue like this requires immediate attention. Turn off your unit to prevent further damage, and call a trained technician for help. 

A rattling sound may also indicate loose hardware within your system or that your system’s motor may be failing. Typically, the louder the rattle, the more serious the issue. But don’t wait for the rattle to become too excessive. Once you notice the abnormal sound, contact a professional immediately. Rattling may also occur when debris such as grass, leaves, and twigs clog the outdoor unit, so keep that area clear and clean.

A Hissing Sound

Your AC’s hissing may be caused by any number of issues. These include refrigerant leaks, valve leaks, and compressor problems. If the unit’s copper tubing has a leak, the high-pressure refrigerant that is escaping may be causing the hissing. Leaks from the system’s internal valve can also make a hissing sound. This should be fixed right away. High pressure might also lead to a malfunctioning compressor that hisses during operation.

Bubbling or Gurgling

Refrigerant leaks often make a bubbling or gurgling sound. You should repair them right away once you discover them. Leaks like this can lead to various cooling issues and repair costs if left unfixed. 

Buzzing Noises

Buzzing can come from motor and capacitor issues. They can mean loose parts, a dirty coil, or electrical issues in the unit. Debris caught in the indoor and outdoor unit may also cause your system to create this sound when operating. 

Screeching or Squealing

Screeching or squealing noises in an air conditioner can indicate various issues, some of which can be quite serious. These include broken components, damaged belts, or faulty bearings. In rare cases, pressure buildup can cause high-pitched squealing. It’s crucial to address these issues immediately to prevent costly damage to your system. If you hear these sounds, turn off your AC and immediately call for emergency service.
If your AC system is making strange sounds, don’t ignore them. Get to the bottom of it with help from an experienced HVAC technician. For all your AC system questions and repairs, please contact the “otterly” friendly and professional team at The Otter Guys now. We also offer plumbing services, new ac installation, ductwork service and more.