Why is My AC Making a Loud Noise?

Loud, surprising noises are the last thing you want to hear from your home. We come to expect certain sounds from our air conditioning units, refrigerators, dishwashers, clothes dryers, and other appliances. Still, a new and unexpected noise can be a sign that something is wrong. When your air conditioner starts up, loud noise could be a regular part of its operation, but it could mean something needs to be repaired.

If your AC is making a loud noise, it’s time to investigate. A.B. May will walk you through what causes these noises, what you can do to stop it, and advise when it’s time for us to make a house call.

If Your AC is Making a Loud Noise, This is What It Might Mean

Banging or Clanking

The part of your AC system that sits outside is called the condenser. The condenser relies on a fan to move air throughout your home. If that fan has come loose or become damaged, it might make noise when it collides with other parts inside the condenser. Depending on the damage, this noise might be louder or more likely when the system starts up. Other parts on the inside unit may have become loose and are banging or clanking against other parts.

Banging or clanking can also occur when your metal ductwork expands or contracts while in use. Temperature changes, such as going from hot to cold, can cause your ducts to contract or expand. Banging may also occur when the dampers open and close if you used a zoned HVAC system. This is a normal noise, for the most part, but if it sounds much louder than normal, it’s time to call A.B. May.

Pulsating

All ACs make a little pulsating sound as they run due to airflow through the entire system. However, if your outdoor unit is pulsating and you can hear it inside, that’s when you’re having a bigger issue with your AC. Something could be loose and rattling around the outdoor unit loud enough to hear it inside. This could be branches or twigs, but most likely, it’s metal from a broken fan blade or motor part.

Clicking

When your HVAC unit turns on or off, you may hear a clicking noise. Often, you’ll never even notice this or grow used to it over time. Constant clicking is not normal, though. A failing thermostat, defective control board, or other electrical issues could cause your AC to click more than it should. We recommend shutting off your AC and calling us to inspect to ensure there’s not an issue that could cause damage to your home.

Whirring

This is not a sound you want to hear your AC making ever. This indicates some mechanical issue with the unit – indoor or outdoor. A.B. May will need to come out and service your unit, potentially replacing it. Bad bearings, a broken belt, a blown fan motor, or faulty blades could cause this helicopter-like sound. Make sure to turn off your unit if you hear this sound and give us a call before it causes more damage to your entire HVAC system.

Buzzing or Humming

Buzzing or humming typically occurs from the outside AC unit. This could mean a variety of things, including:

• Debris is trapped in the unit, like tree branches, leaves, or flowers.
• Outdoor fan or blower is on the fritz or going bad.
• Fan blades are loose or warped.
• Condensor needs to be cleaned from dirt and debris.
• Miscellaneous loose parts.

Rattling or Chattering

The most common culprit of a rattling sound in your AC system is that twigs, leaves, or branches have made their way into the outdoor unit. If that’s not the cause, then parts could be loosening anywhere in the AC unit and might be damaging the condenser as the AC runs. Checking for loose screws or bolts can easily correct this issue, followed by changing the air filter or cleaning the condenser coils.

Squealing

This is not a good sound to hear, especially if it’s sustained as the AC unit is running. There’s a good possibility your outdoor fan motor or indoor blowers are failing. When these parts of the unit malfunction, they make a sound like squealing and amplify through the ductwork. If this begins to happen suddenly, turn off the unit and call us.

Screaming

If screaming makes you jump, your AC doing it will make you jump even higher. If you ever heard your AC screaming, turn the unit off immediately and call us. Screaming often means a refrigerant leak somewhere in the system, and running it will not only drive you crazy from the sound, but it will also continue to damage your AC until it needs to be replaced. In a more serious scenario, your compressor may have too much pressure building up inside it. It’s warning you that you need to turn off the system and get it fixed.

Is Your AC Making a Loud Noise? Call A.B. May Today

Many of the causes of loud noises when your AC system turns on may require a professional. Unless your air filter causes the noise, we do not recommend trying to repair any of the other issues we’ve listed here.

Please leave it to the professionals! If you live in the Kansas City metro area, you can call A.B. May right now.

Read More: Why is My AC Not Working?