Weird Noises Coming from Your AC Unit?

May 15, 2020
woman at home confused


The increase in the amount of time you are spending inside this year may have you firing up the old AC unit a little earlier than years previous. So what should you do when you start hearing an odd, unfamiliar noise coming from your AC vents? Here is what you should know about these weird noises, from the AC contractor that St. Louis homeowners trust to get the job done right the first time when it comes to repairing their cooling equipment before the summer heat arrives.

Classifying Your AC Noises

Have you ever had to describe the noise your car was making to an eagerly awaiting mechanic? It can be an exercise in futility and humility. Here are some examples of sounds your air conditioner may be making, and the potential causes of those noises to better prepare you (and your SmartHouse AC repair technician) for diagnosing your AC issues. 


If you are hearing what sounds like a hive of bees hooked up to an electrical current coming from your air vents or your outdoor condenser unit, you are likely experiencing one of the two most common problems that occur with air conditioners:

  1. A locked up or shorted out compressor or fan motor, or

  2. A failed capacitor

When an electrical component like a compressor or blower motor tries to start, but is unable, it often makes a distinct buzzing sound.  Allowing the buzzing to continue puts your system at added risk of burning itself out, so the best course of action is to turn off the power to your system immediately, and call the SmartHouse Team. 

Failing capacitors can easily be identified and fixed, but should always be replaced by a certified HVAC technician. 


Though some clicking sounds are common during the start-up and shutdown of an air conditioner, if the sound persists it could mean there is an electrical issue like a faulty relay or switch. SmartHouse can locate the failing part, and replace it properly to get your AC up and running at peak efficiency. 

Squealing or chirping

A squealing noise can be jarring, and annoying. A persistent squeal can indicate that a fan or blower motor is out of alignment, or damaged. This issue should be fixed by a professional before it causes further damage to your cooling system. 

Thumping, Banging, or Rattling

A loose part within an air conditioner can be the source of many different sounds, like low thumps, loud bangs, or intermittent rattling. Because of the unknown nature of what and where this part may be, it is important to turn your AC off immediately and call a professional.

You See Ice or Frost Forming on Your System (OK, it’s not a noise but it’s important!)

Even in the heat of the Missouri summer, an air conditioner condenser can freeze. This is usually due to low refrigerant levels, and when the condenser coils or pipes cool down to below freezing temperatures, they freeze any moisture in the air nearby. While it seems like ice should help the air conditioner work, it actually does very much the opposite and your system will not cool properly!

The best action to take it to call SmartHouse and our technician will come running!  Also, be sure to turn off your system so the ice can start to melt.  We can’t fix it until the block of ice thaws!

Not Sure? You Can Still Benefit from AC Maintenance

Even if you are only hearing a weird noise coming from your AC unit or your ductwork every now and again, you may still stand to benefit from calling in the SmartHouse HVAC experts for regular maintenance (or better yet, signing up for a yearly maintenance plan). In diagnosing your cooling problems, we can locate other areas to increase the efficiency of your cooling system, or even recommend an affordable Daikin heat pump or AC replacement that will save you money in the long run (especially when compared to multiple AC repair costs!).

Amidst all of the unknowns of the COVID-19 outbreak, SmartHouse is doing everything in our power to operate safely, and keep the health of our customers throughout Brentwood, Clayton, Creve Coeur, Kirkwood, Overland, Ladue, Richmond Heights, St. Louis, University City, and Webster Groves as our top priority. Learn more about the precautions we are taking here.

If your AC is making noise, it may be telling you something. SmartHouse can translate your AC sounds into quiet comfort and efficiency. Schedule AC maintenance today by calling or get in touch here.