Common Air Conditioner Noises and What They Mean

Common Air Conditioner Noises and What They Mean

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Are you tired of listening to air conditioner noises when you’re just trying to relax and enjoy the day? They are troublesome and not just because of the disruption they cause to your peace and quiet. Noises from your cooling system indicate a variety of equipment issues that may require an HVAC contractor to solve and stop damage to your system.

Learn how to decode common air conditioner noises with the key below. Our NATE-certified technicians also share which noises mean, “call us quickly!” and those that simply say, “annoying but harmless.” If you notice any noises that fall under that first category, call Estes Services right away for fast, effective air conditioning repair!


Whistling air conditioner noises are a tell-tale sign of duct leaks. As the cooling system forces air through the ducts to your living areas, air that is pushed through air leaks may make a whistling noise as it escapes the ducts. 

If you hear this noise, investigate the ductwork you are able to access. Look and feel around for escaping air, obvious damage and signs of previous repair, such as duct tape. Use mastic to seal up any minor leaks . If you are uncomfortable tackling this job yourself, call your HVAC contractor to inspect for air leaks and seal duct leaks – this service eliminates the whistling air conditioner noises and improves the efficiency of your cooling system!


Buzzing noises heard from the outside air conditioning unit can mean any number of problems, including debris in the unit, loose parts or the filter needs changing. If you hear buzzing noises – and it’s not an angry horde of bees – call Estes Services as soon as possible to investigate what is causing the noise. Leaving the symptom untreated could lead to an expensive repair in the future.


Electrical parts often begin to click when air conditioners start up and shut down. Clicking noises may also be a sign of loose parts or parts brushing against other components while the system runs.

Constant clicking is not normal and may point to a defective control panel, poor electrical connections or failing thermostat. There are many electrical components in your air conditioner, which requires preventative maintenance to catch problems early on. Schedule this service with your HVAC contractor each year.


Clanking air conditioner noises indicate a component is out of balance or loose within the air conditioner somewhere. The compressor might be loose, or components within the sealed unit might have failed, requiring a replacement part. A qualified technician will know if the clanking is from a broken component or if the fan blades are unbalanced. These problems need to be addressed immediately to avoid bigger problems down the line.


A chirping noise from your air conditioner is a typical indicator of friction between parts without the correct lubrication. Possibilities include:

  • Dry motor bearings
  • Worn out fan belt
  • Fan rubbing against blower cage or coils

When it comes to air conditioner noises, chirping is the best one you could ask for, as it typically does not indicate serious problems with your system. When you notice chirping from your AC unit, let it run and listen.

  • If the noise gets softer or occurs less often, it’s not urgent. Take a note and inform your HVAC technician of it at your next maintenance tune up appointment. 
  • If the noise persists, call your HVAC contractor to perform the maintenance tasks required to eliminate the noise for good.
  • If the noise develops into a squealing sound, there is a serious issue present somewhere in the system – possibly a malfunctioning condenser or fan in the outdoor unit. Turn off your air conditioner and call your HVAC contractor for AC repairs.


Gurgling air conditioning noises indicate refrigerant line problems. The likely cause is air caught in the lines – a clear sign of a refrigerant leak. The lines are supposed to be sealed to allow no air inside. If there is gurgling, a leak has clearly formed, which has let air into the system.

There is nothing you are able to do to correct this – an HVAC professional must perform repairs, as a license is required to work with and handle refrigerant. If you fail to have this issue addressed, you run the risk of your air conditioner’s evaporator coils freezing over, which restricts performance and has the potential to cause the entire system to fail.


Banging noises coming from your air conditioner indicate something might be loose or broken in your unit. It could be a piston pin, crankshaft or connecting rod banging around inside the compressor. Even an older or unbalanced compressor can produce banging noises.


A high-pitched squeal from your air conditioner can indicate a few different issues with your system:

Outdoor Unit

  • Bad fan motor bearings
  • Bad compressor

Both these issues require the attention of a professional, as both require replacement of the component to eliminate the noise and improve system performance.

Indoor Unit

  • Bad blower motor bearings
  • A worn or misaligned blower motor belt
  • Blower motor malfunction
  • Worn out blower motor

If you are handy, fixes for the first two indoor unit issues are a simple DIY project. The squealing blower motor bearings require lubrication.

  • Turn off power to the indoor unit via the main electrical panel and verify disconnection.
  • Remove the access panel to the blower motor chamber.
  • Locate the oil ports and remove their caps or access plate. They are located over the bearings close to the motor shaft. If there are no ports, the motor is sealed and is unable to be lubricated. Call your HVAC contractor to assess the system for repairs.
  • Add two to three drops of 10-weight non-detergent motor oil in each oil port.
  • Replace caps and access panel, then restore power to the system.

The fan assembly belt needs to be replaced – simply follow these directions:

  • Shut off power to the indoor unit at the home’s electrical panel and verify electricity is disconnected before you continue.
  • Remove the access panel to the blower motor chamber.
  • Loosen the motor’s mounting bolts.
  • Shift the motor slightly toward the blower to loosen the belt.
  • Slip the old belt off and determine the replacement belt size required.
  • Once you have a new belt, thread it over the pulley on the blower, then over the pulley on the motor.
  • Pull the motor back into position.
  • Keep tension on the belt with one hand as you tighten the motor’s mounting bolts.
  • Push on the belt to check tension – it should deflect around half an inch. If the tension is too tight or too loose, loosen the motor’s mounting bolts again then readjust tension and re-tighten the mounting bolts.
  • Reinstall the access panel, restore power and turn on the system to test blower operation.


High-pitched screaming noises are never a good sign. In an air conditioner, too, it’s a major warning sign. Turn the air conditioner off immediately and call Estes Services right away. The normal cause of such noise is a refrigerant leak, which can damage the unit and harm your family’s health. Screaming noises can also signal high internal pressure in your compressor, which can be extremely dangerous. If your unit turns on and then off, it means the sensor is still working – just don’t wait too long before seeking help for the screaming noises.

Is Your Air Conditioner Singing Its Swan Song?

If the noises are determined to be your air conditioner signaling it’s on its last leg, Estes Services can help with installing a correctly sized air conditioner to restore your comfort. Current models are quiet and dramatically more efficient than those produced as little as a decade ago. A newer air conditioner can improve your energy spend from 20 center of every dollar to as little as 3 to 5 cents. Estes Services is here to educate you on all your air conditioning options, including ductless!

End Air Conditioning Noises with Estes’ Help!

Tired of air conditioner noises disrupting your day? You don’t have to tolerate the disturbance any longer if you call Estes Services to schedule air conditioner repair! Let us send our NATE-certified AC technicians to find the cause of the menacing noise and perform effective repairs that mute it indefinitely.