Listen to Your AC Unit – Is Sound an Issue?

Listen to Your AC Unit – Is Sound an Issue?

Posted by
Ed Miller on Sat, Dec 15, 2012

If your AC unit makes odd sounds when running or even when not, you might be able to determine exactly what the sound is indicating. It is important to have an HVAC technician evaluate the problem and offer a solution to correct it.

Common complaints with air-conditioning units often involve a disturbing noise from the outdoor compressor that bothers the neighbors. The hardest working component of an air-conditioning system is the compressor, which squeezes vapors of Freon into a liquid gas, which is then sent back into the home through tubing. The compressor is large component that often generates a lot of noise, and can run continuously for hours at a time. Even a single unit can cause significant amount of disturbance in the neighborhood, especially if it becomes defective or old. When that happens, it might be time to call in a licensed HVAC contractor.

Older, outdated air-conditioning systems were typically built with 10 seer efficiency. By today’s standards, the units are very inefficient, loud, and produce only minimal amounts of cool air. Other AC units and heat pumps can generate banging sounds that might be caused by loose fan blades or broken fan shaft. Many times a bent screen around the fan can get in the way of the blade and generate a loud noise.

A Grinding Noise

Older AC units can often generate grinding noises, which sound like a rattling, banging or a clang. This is usually a result of a rotating shaft that is become wobbly or from motor mounts that have loosened.

Loud Buzzing Sound

Loud buzzing sounds from the air conditioner or your heat pump are usually a result of the central unit freezing up or from water dripping on the fan motor. When left without repaired, they can start generating loud noises. A simple repair might be nothing more than adding more refrigerant or finding out what the obstruction is.

Loud Humming Sounds

Humming or hissing sounds inside the AC unit or heat pump system might indicate that there are failing electrical parts or components. Old condenser fan motors or failing electrical components can raise the potential of a fire risk.

Loud “Thunk” Noise

If your AC unit is generating the sound of a loud “thunk”, that mimics tennis shoes in a moving dryer, it may be a result of a loose fan, an unsecured motor mount, or other large moving component in the unit.

Loud Rattling Noise

Rattling noises from your AC unit can usually be traced back to a bad fan shaft bearing, or a motor mount on the fan that is become loosened. It might also be produced by a ticking sound whenever the fan hits an obstruction.

Whenever you hear odds sounds from your AC unit, it is important to call a licensed, bonded HVAC contractor right away who can evaluate the problem and offer to make repairs.



routine maintenance,


Air Conditioning

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