Air Conditioner Noises and Their Implications -- Know When to Call in Your HVAC Tech – Sobieski Services | DE, NJ, PA, MD

Air Conditioner Noises and Their Implications — Know When to Call in Your HVAC Tech

Air conditioners are complex systems with components that extend throughout your home. Usually, these parts work together quietly and effectively, producing very little noise beyond the sound of air moving through the ductwork or the air conditioning unit switching on and off. When loud or unfamiliar air conditioner noises occur, they likely are signaling that something is wrong somewhere within your cooling system. In most cases, air conditioner noises will mean a visit from your local trusted HVAC professional. Here is a brief guide to the types of air conditioner noises you might hear and what could be causing them.


  • Clanking or rattling sounds: If the internal mounts on the compressor are loose, they can cause rattling and clanking sounds. A serious noise of this type can mean the compressor has come loose from its mountings and is moving around inside the cabinet. It can also mean the compressor is about to fail.
  • Banging or clanking: A loose part within the compressor, such as a connecting rod or piston pin, can cause these noises. Replacement of the compressor usually will be necessary to stop them.
  • Bubbling or hissing: A refrigerant leak can produce bubbling or hissing sounds in the compressor. Have the leak fixed as soon as possible to reduce exposure to refrigerants. In most cases, the louder the hissing the worst the leak.
  • Clicking or snapping: Malfunctioning relays or other controls could produce clicking sounds if they fail to function.
  • Ticking, rattling or rumbling: Loose hardware or system components near the compressor could produce these types of sounds.
  • Hissing or “screaming” noise: If the compressor is producing a loud hissing or screaming noise, it could be a sign of dangerous pressure build-up inside the compressor. Shut the compressor or entire air conditioning system down and call for repair. Condenser and other internal components
  • Buzzing or crackling: These types of noises can be caused by electrical problems within the system, such as malfunctioning or arcing electrical connections. Electrical issues are potentially dangerous, so shut down the air conditioner and call for repair immediately.
  • Squeaking or squealing: Moving parts within the air conditioner may need to be oiled or lubricated to prevent squeaking or squealing sounds. Fan motors are common sources of these noises.
  • Clicking or snapping: Malfunctioning thermostats, relays or other controls can produce these noises. Call your HVAC professional for replacement.
  • Bubbling, hissing or spraying sounds: A leak in the refrigerant line could be responsible for these sounds.


  • Rattling, clattering, tapping or banging: Loose sections of ductwork can cause rattling and banging sounds as the sections hit against each other. You or your HVAC pro will have to reseat the loose sections and make sure they fit tightly together. Animals such as squirrels or raccoons in the ductwork may also be responsible for loud noises. It could also require the services of a professional to remove the animals and repair any damage they’ve caused.
  • Clicking, ticking or cracking: These noises can be caused by the ductwork itself expanding or contracting as cool air flows through the system. Even small movements of the metal ductwork can cause sounds as it rubs or taps against your house frame, other structural components, or other pieces of the ductwork itself.
  • Hissing, whistling or roaring sounds: Movement of air within the ductwork will produce some minor sounds, but serious noises could indicate a significant air leak or broken seal in the supply ductwork. If the leak continues, you’ll lose substantial amounts of energy and money as cool air is lost. Contact your HVAC professional for a system maintenance call and duct resealing.

Our goal is to help educate our customers about Plumbing, HVACR, Fire Protection and Alarm Systems in Mechanical, Commercial and Residential settings. For more information about air conditioner noises and what they mean, and to view projects we’ve worked on, visit our website! We provide quality services in Delaware, Pennsylvania, New Jersey and Maryland.

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