What's Causing That Strange Sound Coming From Your Air Conditioner

20 September 2021
 Categories: , Blog


Air conditioners make a variety of sounds during normal operations, but when you start hearing something new, this is usually a sign your air conditioner needs attention from a specialist. Sounds like these necessitate maintenance or repair to prevent problems from getting worse and more expensive to address.

Popping and Banging

Loud popping and banging sounds may be the most startling, but also may indicate problems of lower severity. These sounds typically come from your ducts, often when your HVAC system starts up. There are a few different reasons these sounds can occur, but they usually point to a large difference in air pressure between ducts returning air and those supplying it to your home. This in turn can be caused by ducts that are losing their seal or insulation, an air filter that needs to be replaced, or dampers that need to be adjusted.

While fixing this problem requires duct maintenance, it also usually means there's nothing wrong with the actual mechanics of your HVAC system. Still, it should be addressed quickly to keep your energy efficiency up and to avoid any further duct damage.

High-Pitched Squealing or Shrieking

Squealing and shrieking almost always point to an issue with moving parts. You'll often hear these sounds when belts begin to dry, crack, or loosen, and they can also be caused by worn-out bearings on the condenser fan.

Because these problems come from moving parts, avoid using your air conditioner as much as possible until the problem can be fixed, as physical damage to these parts can very quickly escalate. These parts typically aren't too difficult to have replaced; the problem comes primarily from letting damage get worse.

Metallic Grinding

Grinding sounds also indicate an issue with moving parts, but these sounds can often come from parts behaving in a way they shouldn't rather than parts simply wearing down. They can be caused by the same types of issues that cause squealing and shrieking, but you may also hear them if, for example, fan blades are misaligned and hitting other mechanisms, or if bearings in the fan motor have worn down such that they are almost completely ineffective.

If you hear these sounds, avoid using your air conditioner if at all possible until it can be seen by a professional.


Rattling sounds can indicate parts damage, but can also point to more innocuous problems like debris in your outdoor unit being hit by fan blades, or loose bolts, nuts, and screws. If there are no more serious issues causing the problem, then it's likely your unit just needs some standard maintenance like making sure the outdoor unit is cleaned, that fans are aligned, and that everything is lubricated and tightened as needed. If you can't immediately identify the problem, it's better to be safe and wait until a technician can come out for inspection and maintenance before continuing to use your air conditioner.

To learn more, contact a company like Baton Rouge Air Conditioning & Heating.