central AC unit outside house in grassy yard
June 16, 2021

The last thing you want to hear when you turn on your air conditioning on a hot Oklahoma day is an odd sound coming from your vents or the air conditioning unit itself. But if you aren’t mechanically inclined or familiar with central AC noises, you might be wondering whether the sound you’re hearing is normal or evidence that you need to call a professional to check your system out.

Here’s a quick breakdown of the different sounds an AC can make, and which ones you can immediately forget about versus which ones you should be on the lookout for.

Normal Sounds Your Air Conditioning Can Make

If your cooling system is making one of the sounds described below, you can breathe a little easier—it’s likely operating as intended!


If you hear your air conditioner make a sound like a plane taking off when it first kicks on (only not as loud, obviously), that’s normal operation! Air conditioners have a lot of moving parts, and there will be a brief series of startup-related sounds.


It’s also normal if your AC clicks once or twice right at the end of the cycle, before powering down—this is the sound of the different machinery coming to a stop.

Loud Outdoor Unit

If your outside AC is making loud noises, it might not be a sign of an air conditioner that’s broken or in need of repair, but simply an older, aging model. You might not even be able to hear it inside your home, but it’s probably not your neighbor’s favorite sound to listen to. While a loud outdoor unit likely isn’t cause for concern, it is a good sign that you could benefit from an AC upgrade—today’s cooling system models, from central AC to ductless mini-splits, are not only much quieter but more energy efficient as well, saving you money.

AC Sounds That Could Be the Sign of an HVAC Problem

Hearing any of the sounds below? Our recommendation is to call an HVAC expert to take a closer look at your air conditioner and make sure there isn’t an issue that needs repairing.


A buzzing noise coming from your air conditioner could be caused by several issues, including:

  • Loose parts vibrating

  • An issue with the condenser fan

  • Electrical problems


Is your AC making a constant high-pitched squealing noise? It could be an issue with the bearings on your condenser motor, or a belt issue if your unit is an older model.


A pulsating noise from your outside air conditioner unit might not be cause for concern if it’s at a low volume, but if it’s loud enough that you can hear it inside, the coil fan or motor fan blade could be to blame, and you’re better off getting it checked by a professional.


If you’re hearing a whistling sound from your HVAC system, it’s likely coming from your vents. Whistling noises are primarily caused by airflow issues. This could signal that it’s time to check your air filters to see if they’re completely clogged and restricting airflow through your ductwork! Not only can this be annoying to listen to, but it can add unnecessary wear and tear to your AC itself and lead to more frequent AC repair calls.

Need AC Help? Call the Experts at DeHart!

Hearing some other sound that we haven’t covered here? Not sure whether the noise you’re hearing is normal or a sign of a cooling system problem? That’s what DeHart is here for! Our family-owned team has been in business for over 100 years, and our crew has been helping generations of homeowners in Duncan and Chickasha stay cool in the summer and warm in the winter, with everything from repair to regular HVAC maintenance and tune-ups.

Need an expert’s opinion on the noise your AC is making? Call 405-224-0184 or contact us today to talk with the local technicians who know Oklahoma.

Is your AC buzzing, squealing, or clicking?

Find out what’s going on with help from DeHart!


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