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5 Strange AC Noises & What They Mean

Monday, July 3rd, 2023 at 11:00 am

Your air conditioner works great, until it doesn’t. The good news is that before your air conditioner breaks down completely, there are some signs that you can pay attention to indicating trouble. The easiest signs to look for are unusual sounds. 

The question is, which air conditioning sounds are normal and which are not? Plus, just because you hear an unusual sound doesn’t mean you know exactly what is wrong. The good news is, that’s what our team is here for. When you need AC repair in Saint Augustine, you can give us a call. In the meantime, you can keep reading to learn more about five unusual AC noises and what they might mean.

Hissing or Bubbling

If your air conditioner begins to make a hissing or bubbling sound, that’s a sign that you have a refrigerant leak. The refrigerant inside of your air conditioner alternates between gas and liquid form during the cooling cycle. In its gas form, a leak will make a hissing sound. In its liquid form, a leak will make a bubbling sound.

One problem with hissing and bubbling is that the sounds can be fairly quiet and you have to listen closely to hear them. Not all strange AC noises are loud or obvious. This is why it’s important to take time once in a while to pause and really listen to your air conditioner during a cooling cycle.


Any time you hear a sound that is metal scraping against other metal, this is a big red flag. Something inside of your air conditioner is either off balance or malfunctioning. The scraping sound may be inside your AC motor or it could be a fan blade that is bent and scraping on a wall. 

No matter the scenario, scraping is always a problem. In fact, when you hear scraping you should turn your air conditioner off right away and leave it off until one of our technicians can check it out. Otherwise, you run the risk of damage affecting other parts of the system.


This is another sound that may originate in your AC motor. As the motor loses some of its lubrication over time, the result is a grinding sound. The motor loses lubrication because dust and dirt build up inside, drying it out. You can prevent grinding by scheduling annual AC maintenance. Our team can clean out dirt and resolve any other problems to prevent additional damage.


Rattling is quiet and a little less serious than the previous two sounds, but it still deserves immediate attention. Rattling can indicate that a small part is loose somewhere in the AC and moving around. Your AC unit may still be working great, but the loose component that is rattling around runs the risk of leading to more damage. 


It’s totally normal for your AC unit to click on and off at the beginning and end of each cooling cycle. But you should not continue to hear clicking sounds as your unit continues running. Clicking can be difficult to identify because it’s often quieter and less threatening. But clicking may mean that your AC is struggling to turn on or stay on for the cooling cycles. 

Climate Masters: Serving St. Johns County since 1988 with quality, hometown service. Schedule an appointment today for AC service.

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