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It’s so hot outside, and you weren’t ready. Your central air conditioning system is getting more usage than it typically does in the winter. There seems to be a problem though. It’s making a noise you’ve never heard before. 

Noises don’t always indicate that your system requires replacement or expensive repairs. Sometimes, the cause of the noise is much simpler. Before you panic, here are some of the common noises AC systems make and what it means.

Ten Categories of AC Noises

When considering noises, we categorize them in ten ways. Here are the noises that you might experience.

  1. Bangs

Banging is pretty common, and it is often a simple fix. One of the most common causes is that something like dirt, leaves, or twigs has found its way into the condenser. Clean it out. If any bushes have grown too close to the outdoor unit, take care of them by trimming them back.

If the AC fan is loose, it may start hitting the case. That can cause a banging or snapping noise. You’ll need to talk to an AC technician to see if the fan can just be tightened or if it has to be replaced.

Once you’ve removed the item, the noise should disappear. If it hasn’t, you might have a broken motor or compressor. That is going to be a more expensive repair. If your AC system is older than ten years, you should consider a new AC system. Home Advisor estimates the average cost of an AC condenser repair to be around $2,100. With federal tax incentives and Florida AC rebates from FPL, you may find yourself breaking even with a replacement over the repair.

  1. Bubbling

When your condensate line is clogged with dirt, algae, or other grime, the water in the drain pain may bubble. Water can’t leave the pan, so it will start to make bubbling noises. If the condensate pump is damaged and isn’t pumping out condensation properly, it is also going to lead to a bubbling sound.

  1. Buzzes

Buzzing noises occur when the AC compressor is still drawing power after it shuts off. If the unit isn’t sending the signal correctly to stop drawing power at the end of a cycle, you need to have the compressor replaced.

The AC capacitor and motor are other reasons you might hear buzzing. The capacitor stores electricity and releases it as needed. If it’s not working correctly, the fan won’t turn on.

  1. Clicks

Clicking is usually something related to the electricals. If the capacitor isn’t holding a charge, it will click to start the compressor, but the lack of built-up power prevents the compressor from actually starting.

Poor electric signals in switches can also cause them to turn on and off rapidly, leading to clicking noises. If this happens, it’s important to turn off the unit and wait for your AC technician. Electrical issues are not something to try to fix on your own.

  1. Cracks

Are you hearing a cracking noise, one that sounds like ice that’s melting and cracking? If your coils are building up ice, this noise may appear. You need to get into your AC unit and clean the coils and fins. If you’re not sure you can do this, call an AC technician.

  1. Hisses

When you hear a hissing, it’s usually a leak of Same Day Service or a leak in the compressor valve. Both of these issues are not something you can resolve on your own. You need to hire a professional for AC repairs.

  1. Hums

What causes a humming noise? One issue is easily fixed on your own. Check the aluminum fin coils on the AC. If any of them are bent, it can cause a humming noise. Use a fin comb to straighten them back to the correct orientation. This is part of a routine AC cleaning, so it’s less likely to have humming caused by bent fins.

It may be a problem with the lubrication in the motor. Most motors are sealed, which makes it hard to lubricate them on your own. You should ask a professional for advice. 

The other common cause of a humming noise is a problem with the electricity contactor. If it’s not getting a good connection, the power supply cannot get the right amount of power to start back up. It will hum instead.

  1. Rattles

Rattles are often tied to loosened components like a loose screw that starts to vibrate. Look over your unit and see if any screws need tightening. Take a screwdriver and tighten everything and see if that resolves the issue. If it’s still rattling, it’s time to call in an AC professional.

  1. Screeches

Screeches are usually one of two things. The compressor could be experiencing high pressure. If this is happening, turn off the unit and call a professional to have the system pressurized before the pressure blows something. The bearings inside the fan motor are the more likely culprit. When a bearing is going, the sound of metal scraping on metal is shrill.

Some systems have fan belts. If your system has a belt, the belt could be breaking or loose. Humidity can also impact a belt, so it’s important to have the system examined by a professional AC technician.

  1. Whistles

Whistling noises are usually a sign of a leaking duct. Air is escaping into a wall or attic. It’s not the most alarming noise, but it’s one you should address as it can make your AC run more often or longer. Schedule an appointment for duct repairs, but you could use duct tape to seal a hole or crack for now, provided you can find it.

If you have a dirty air filter, it might be creating a whistling noise. It makes it harder for the blower motor to push air through the filter, which will result in a whistling noise. Change your air filter and see if the noise stops.

Don’t Ignore the Noise or Try to Fix It Yourself

Don’t try to diagnose an unusual AC noise by yourself. If you’re wrong, you could end up making it worse. If you ignore it, it could get a lot worse and damage your system. Work with a Florida AC repair expert to get your system up and running. 

All Year Cooling offers a full AC system evaluation with every service call. We have been in business for 50 years, and our AC technicians are experts in the field who undergo continual advanced training to stay current with technology and advancements in AC equipment and designs.

We’re available 24/7 throughout the year. If you’re hearing a loud, concerning noise coming from your AC system, call us. Our estimates are free and clearly laid out so that you understand what work is being done. If the repair isn’t going to keep your system running, we’re always honest about the benefit of the replacement of an older system vs. repairs. Reach us by phone, chat, or online contact form.


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