Why Does My Air Conditioner Make Noise After It Shuts Off?

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Updated August 13, 2022

Even the best air conditioners can run into problems. Whether you have an indoor or outdoor unit, everything from the air filter to the condenser fan motor can go on the fritz. If you’re trying to figure out why your air conditioner is making a loud noise when it shuts off, you’re in the right place.

KEY TAKEAWAYS:

  • There are several causes behind a higher noise level than usual or unusual noises. You’ll need to troubleshoot to figure out the root of the issue.
  • Air conditioner noise doesn’t always mean that you’re out of luck as far as repairs go. However, it’s never a bad idea to check into your extended warranty if you have one.
  • Different noises will mean various problems, although some can sound similar. For example, hearing a rattling noise means something other than a loud banging.

Before you begin, though, you should already know a little bit about basic troubleshooting an AC. If not, try reading up on how to find a leak in a central air conditioner and similar articles.

Causes Behind a Loud Noise in Your Air Conditioning Unit

Many issues can pop up with an air conditioner, some leading to expensive repairs. For example, you might have a problem with your air conditioner stinking when you turn it on.

Insider Tip

Sometimes you can perform a compressor replacement yourself if you understand the physical and electrical components.

If what you’re hearing is a strange sound, that can cause panic. Don’t worry too much until you’ve investigated the issue, however. Some simple reasons could explain it, and we’ll go over those below.

Of course, should you discover you need a new unit, do your research before buying, like reading our Goodman Central Air Conditioner review. It’s a solid option if worse comes to worst and you need a new model.

Air Ducts

The sheet metal comprising your air ducts is susceptible to temperature changes and will expand and contract. When you turn off your air conditioner, the noise you’re hearing might just be the sheet metal ducts expanding once the heat starts to seep in.

If your unit is blowing cold air in the middle of winter, read up on why your air conditioner is running when the heat is on.

Damper Closing

Dampers direct the airflow throughout your home, allowing you to close them in specific rooms and while pushing the cold air to more important rooms. If you’re hearing a slamming noise, it may be a damper on one of the ducts closing when the unit shuts off.

If this is the case, you’ll be able to tell because it makes creaking noises rather than a slamming sound. This isn’t necessarily a cause for concern, unlike issues like the air conditioner running when turned off.

Blower Fan

Check your blower motors and fan blades if you hear a loud sound when you shut off your air conditioning unit. The most likely cause is that something has come loose and is banging around the unit’s housing.

Warning

Make sure you keep your air duct clear by regularly cleaning it and the filter. A dirty filter can cause a whole host of problems.

F.A.Q.S

What should I do if I hear strange noises coming from my AC?

Any loud AC noise can be particularly upsetting. You should likely call an AC repair company and see whether any minor repairs must be made.


Is an outdoor unit better than an indoor one?

Neither is notably better than the other. There are just some key differences between them that you should consider. Most systems are split between the two, however.


What type of noise is a bad sign from my AC?

There will likely always be a humming sound coming from your unit. If the indoor noise level is high, you might have a problem. Any noise can be negative, depending on the volume. Here are some to watch out for:

  • Pulsating noise
  • Rattling noise
  • Bubbling noise
  • Clicking noise

When should I call an AC repair company?

If you can’t figure out the exact issue, calling out some repair technicians is not bad. Sometimes extensive repairs are required that you won’t be able to do yourself.


STAT: Air conditioners (A/Cs) shipments in the United States reached a peak in 2021. (source)

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