Why is there a weird noise when my AC is on?

Author: Aditya Hermann  |  Last update: Thursday, January 8, 2026

If a small piece of debris gets stuck the fan can't move. The electrical impulse of the fan to move while stuck is the root cause of that annoying buzz. Buzzing is also a significant clue of a potential electrical malfunction in the AC unit. Loose wires, frayed junctions, all these can cause buzzing.

Why does my AC make a weird sound when I turn it on?

If you hear loud buzzing noises from your air conditioner, it's likely malfunctioning. Typically, the issue is either loose parts, missing or broken isolation feet, refrigerant leaks, or a malfunctioning compressor. Every part of your air conditioner works together to keep your home cool in warm temperatures.

Why is my AC making noise when running?

One common cause is a dirty or clogged air filter, which can obstruct airflow and cause the system to work harder, resulting in increased noise. Another possible reason is a malfunctioning fan motor or a loose fan belt, causing rattling or squeaking sounds.

What does a bad AC sound like?

If your AC unit is making loud noises that resemble hissing, it could warn that the compressor has reached a high internal pressure. This issue can also manifest through a high-pitched squealing noise.

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.

5 Common AC Noises and What They Could Mean

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 dying compressor sound like?

Your air conditioner compressor is making unusual noises: If your compressor is making a loud rattling, grinding, or clicking noise, this could be an indication that a piece has broken inside it. If it is more of a grinding noise, the compressor bearings might need to be replaced.

How do you know if something is wrong with your AC?

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.

What does an AC leak sound like?

But a persistent hissing or whistling sound could be a sign of a refrigerant leak. A refrigerant leak could occur in your refrigerant lines or in your internal valve. Leaky refrigerant lines could also make a bubbling sound. Leaky internal valves will worsen if left unchecked, and the hissing sound will intensify.

Why does my AC sound like an airplane taking off?

If your air conditioner sounds like a jet engine, this is a sure sign that it is breaking down. The problem could be a faulty condenser fan, a failing compressor, or frozen evaporator coils.

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.

Is it normal for AC to make loud noise?

However, sometimes air conditioners make too much noise, which can be annoying or even dangerous. It could be a sign that the unit is about to break down or something is wrong with the wiring. In some cases, the noise might be caused by a problem with the fan.

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 long do AC units last?

While every unit is different, and every homeowner has a different understanding of when their central air conditioner is broken beyond repair, it's fair to say that, with proper maintenance and care, you can expect a good 15 to 20 years of cooling from a new high efficiency air conditioning system.

Why does my AC sound like it's hitting something?

A banging noise or the sound of rattling from the indoor unit or outdoor condenser unit is often caused by loose parts. The indoor blower fan may have loose fan blades rattling around as the motor rotates the fan.

Should I turn off AC if it's not cooling?

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

When should I be worried about AC?

If your AC is blowing out warm air, or is just not cooling properly it is a surefire sign that you are in need of maintenance. You may need your air filters replaced, a refill on refrigerant or it could be time to have the AC coils cleaned by a professional.

How do I know if my AC blew out?

In addition to a sudden stop, these signs of blown AC fuses require your attention:
  1. Strange sounds are coming from your air conditioning unit.
  2. Your circuit breaker keeps tripping.
  3. Your unit smells like it is burning or gives off the smell of exhaust.
  4. Water is leaking from the unit.

What does a noisy AC compressor sound like?

Clanking and banging can mean a loose piston pump, crankshaft or connecting rod in the compressor. Bubbling and hissing can indicate a refrigerant leak. Usually the louder the hissing, the worse the leak. Buzzing noises can mean that the motor is failing.

What does a bad AC capacitor sound like?

A sure sign of a bad AC capacitor is a humming sound from within the access panel.

How to tell if an AC compressor is going bad?

What Are the Signs and Symptoms of a Bad A/C Compressor?
  1. A Lack of Hot Air Being Released Outside. ...
  2. Loud or Strange Noises From the Unit. ...
  3. Failure of the Compressor to Turn On. ...
  4. Power. ...
  5. Dead Compressor. ...
  6. Capacitor and Starter Relay Problems. ...
  7. Dirty Coil and Filters. ...
  8. Circuit Breaker Tripping.

Why does my AC make a weird noise when I turn it on?

Buzzing – Buzzing is likely an electrical issue. Clicking – Clicking can indicate you have a loose part or that the fan is misaligned. Pulsating – Pulsating can come from a loose part. Loud Noise – A clear noise from your outside unit can indicate an issue with your compressor, damper, fan or air handler.

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.

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.

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