Is it normal for AC to make noise?

Author: Mr. Jeromy Koss DVM  |  Last update: Friday, May 23, 2025

If you notice your air conditioner making noise when it turns on and off, that's totally normal. But if your system clicks constantly, it could be due to an electrical problem or failing thermostat.

What is the normal noise of an air conditioner?

Therefore, when talking about the interior noise of an air conditioning unit, depending on its capacity, 35 dB is a reasonable interior noise for a split type system. Now, for the exterior noise, it shouldn't be higher than 5 dB.

Should I turn off my AC if it's making noise?

These noises could indicate an issue with the blower, a loose part, or even a failing compressor. Continuing to run your AC in this state can cause more damage. It is best to turn it off and call a professional HVAC technician to diagnose and fix the issue.

Should I hear my AC running?

If your air conditioner makes whooshing a noise, that's also not a problem. You will always hear light and gentle whooshing noises when your AC is on. There's air moving through there that makes a sound. This will get louder as you walk under vents.

What does a bad air conditioner sound like?

If your air conditioner is making a shrieking noise, this is an indicator of an issue with the fan motor. This sound may also be caused by a broken motor in the compressor of the condenser system. A screeching or squealing noise may also be caused by a damaged blower fan motor inside your house.

5 Common AC Noises and What They Could Mean

What does a dying AC unit sound like?

Any noises like rattling, whirring, or any louder-than-normal humming may mean that there are some more significant issues at hand. The normal humming of the AC unit can change to a ticking sound, which can indicate the compressor is struggling to turn on and off.

How do you know if something is wrong with your air conditioner?

Unusual Noises

Most air conditioners make low-level noise as they start up and shut down. But loud, sudden or unusual noises can signal big problems with your cooling system. Rattling or buzzing noises can indicate a loose part, while whistling or grinding noises can signal something more serious.

Why is my AC making a weird noise?

Clanging, Rattling, and Banging

Clanging and rattling noises are a sign that a loose part is hitting another part. For example, the compressor or blower unit. These loose parts will eventually disconnect, which will create an even more loud banging noise. It can sound like someone is shaking keys inside your AC!

How to tell if a thermostat is bad?

A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.

Is it good for AC to run constantly?

While you may have been cautioned against this by well-meaning friends or family, in most cases it's perfectly fine to keep your home's central AC system running continuously.

What is the normal sound of the AC compressor?

Essentially, the only noises you should hear coming from your air conditioner are the whirring associated with its start-up and the constant drone of its operation.

How often should AC be serviced?

It's recommended that you service your home air conditioning system at least once every year. The same goes for your heating system.

How much does it cost to replace an AC compressor?

On average, AC compressor costs range from $800 to $2,300, with most folks paying $1,200 for a new one. However, your price will vary depending on factors like the size and brand of your compressor. Before you schedule your replacement, read on to learn about all AC compressor cost factors.

Is it bad if my AC is loud?

A lot of problems can lead to a noisy air conditioning system. Some of the most common issues include: Loose connections: Electrical connections, nuts, and bolts can all rattle around while an AC unit runs. Damaged blower motors: Air conditioner blower motors can struggle to spin correctly after years of wear and tear.

Why does my AC sound like a jet engine?

A jet engine sound may be produced if the condenser fan in the outdoor unit is working improperly. The noise may indicate an accumulation of dirt and debris within the unit or an electrical issue with the fan.

What is acceptable AC noise level?

In offices and commercial areas, where maintaining focus and productivity is vital, the recommended noise level is between 40 to 60 dB. In these settings, quieter air conditioners are preferred to create a pleasant and conducive working atmosphere. In hospitals and Libraries, the permitted noise levels are set to 40db.

What does a bad thermostat sound like?

If your thermostat is not working properly, you might hear rumbling sounds coming from the engine because the coolant in the radiator is boiling. It could sound like knocking, boiling, or gurgling.

How can I tell if I need to replace my thermostat?

Signs You Need a New Thermostat
  1. Heating or cooling system will not turn off or on.
  2. The temperature reading is incorrect.
  3. Recent spike in your energy bill.
  4. Frequent temperature fluctuations.
  5. Thermostat is 10 years old or older.

How much does it cost to replace a thermostat?

Replacing a Thermostat. You'll pay between $15 and $300 for the unit in addition to labor ($65 to $100 per hour) to replace an old thermostat with a new one. However, installing a brand-new thermostat is more involved and, therefore, more expensive.

What does a bad AC sound like?

The Short Answer Is: High-pitched squealing noise, banging noise, clicking noise, buzzing noise, hissing noise, rattling noise, and other loud sounds coming from your air conditioner all mean there is something within the system that needs to be replaced or repaired.

How do I stop my air conditioner from making noise?

Place Sound Barriers Around the AC Unit

A sound blanket can reduce noise by up to 40%. These blankets wrap around the compressor (typically the loudest component), where the rubber and glass insulation absorbs the noise, trapping it inside the blanket.

Why is my outside AC unit making a humming sound?

A hum usually indicates the steady drive of the outside fan blade and motor, but a humming or buzzing sound could also indicate a mechanical or electrical issue.

How do you know if your AC is about to go out?

10 Signs Your Air Conditioner Needs Repair or Replacement
  1. Air Conditioning System is Blowing Warm Air. ...
  2. AC Thermostat is Not Working. ...
  3. Little Air Blows Out of Vents. ...
  4. Loud Noise Inside of the AC Unit. ...
  5. Strange Odors When AC Turned On. ...
  6. Not Enough Humidity Removed By the AC. ...
  7. Problems with the AC Are Occurring More Often.

Should I turn off my AC if it is not cooling?

Yes, you should turn off your AC if it's not cooling.

How long do air conditioners last?

It's important to be aware of how long air conditioners last, so you don't get the unwelcome surprise of a broken air conditioner in the peak of the summer heat. In general, air conditioners that are properly maintained can last 15 to 20 years.

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