“Is my air conditioner supposed to sound like that?”

If you have to ask, it’s probably not. What it’s supposed to do is make your home life more comfortable.

Besides, being quiet isn’t just a selling point of HVAC systems. It’s required by law. HVACs that operate too loudly legally count as noise pollution.

So, if your AC sounds loud, obnoxious, or just plain strange, there’s obviously some sort of problem. And we’re going to help you figure out what that problem is.

Below is a short but complete guide on different AC noises that indicate something’s wrong. Read through this checklist to discover what’s causing the noise and what to do next.

1. Flapping or Rattling

A flapping or rattling noise usually means there is debris in the outdoor unit contacting the fan blade as it spins. Most often, this debris is leaves, paper or plastic litter, or small twigs that blew into the system via a strong gust of wind. Another common cause is that crawling vines are creeping into the system as they grow.

Whatever the cause, go to your outside compressor unit and check it out for yourself. Vines are easy to pull away manually. And it’s very important that you do since they will shove, pull, and crush the unit until it is destroyed.

Other debris can also damage your system. But don’t shove things into the unit or dismantle it to remove the debris or you could damage yourself.

If you can easily remove it yourself, do so. Then, turn on the system to see if this solves the problem. If the debris is out-of-reach, or the sound persists after you remove it, call a professional to fix it.

2. Banging or Clanking

Most of the time, banging or clanking noises mean that some component of your AC system has come loose. The loose component, or the unit itself, may be wobbling around during operation, causing the noise.

Alternatively, there may be a bent or dented component, such as the fan housing, that’s contacting the fan as it spins. These issues can also cause a rattling sound.

Obviously, you don’t want your system operating under any of these conditions. For one thing, neither you nor your neighbors should have to put up with that unbearable racket. And, more importantly, this could wear down your AC system or its components much faster than normal.

Have an HVAC technician check it out as soon as you can.

3. Buzzing Noises

A low hum is normal for AC systems. But if it sounds more like buzzing, that’s not normal.

There are many different issues that may be causing it, including:

• A loose blower motor, fan blade, or other loose component
• A worn-out condenser coil
• An air filter that’s full to capacity
• Debris contacting the fan blade
• The copper lines contacting themselves or some other metal
• A refrigerant leak

That last example, a refrigerant leak, is very serious. It can poison anyone in the vicinity.

If you see moisture/puddles around your AC system, or the air from your AC isn’t cold, shut it off now. Call an air conditioner repair company for emergency repair service.

Otherwise, step one when you hear buzzing is to change your air filter. If the noise doesn’t stop, get it checked out by a professional.

4. Clicking (Inside or Outside)

Many AC systems click once when they turn on or shut off. This is just the electricity clicking on/off.

Frequent clicking, though, is abnormal. If you hear this, try to figure out if it’s coming from inside or outside the house.

Inside Clicking

Indoor clicking is probably some sort of electrical problem. Certain wires in the system might be touching where they’re not supposed to. Or, the thermostat or some other electrical component might be malfunctioning.

Regardless, electrical problems could start a fire. Shut the system off and call for emergency HVAC repair.

Outside Clicking

If the clicking is outside, it’s probably a loose component that’s causing the noise. However, if it’s very loud, it might be the sound of a capacitor dying. You need it fixed either way, though, so call it in.

Slow-to-Fast Clicking

If the clicking starts slow and then speeds up, the fan is scraping against something while it spins. Check the outdoor unit for debris or components contacting the fan blade.

5. Popping Sounds

That loud, metallic popping noise that happens once in a while is coming from your ducts. Poorly-insulated ducts will contract or expand based on temperature changes. When this happens, it sounds like someone punching sheet metal.

Unfortunately, there are only two things you can do about this. Installing additional insulation around your ducts may solve or, at least, quiet this disturbing noise. If not, you may need to replace your ducts or the entire system.

6. Screaming or Whistling

A loud screaming or whistling sound could also indicate a refrigerant leak. As we instructed above, turn off the system and call for emergency HVAC repair.

Another possible cause is that there is excess pressure built up in your compressor. This, too, is dangerous. But, usually, the HVAC can detect this and will automatically shut down if this happens.

However, if the whistling is quiet, it’s probably just a clogged or leaky air duct. See if changing your air filter helps. If not, your ducts may be excessively dirty or too small.

7. Any Change in Operating Noise

Lastly, if the noise has only started recently, it’s obviously not normal. That’s especially true for AC noises that are constantly getting louder.

As a general rule of thumb, if it sounds weird, it is weird. Always have a professional HVAC maintenance service inspect any changes that occur when operating your system.