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Why is My Air Conditioner Making that Noise?

What is wrong with your air conditioning system? If it’s whining, humming, hissing, or just plain loud, your air conditioner may be telling you that there’s a problem brewing. Here’s what you can do to stop that sound and guidelines for when it’s best to call in a professional.

Your HVAC system helps you keep your air temperature comfortable and also helps keep your indoor spaces well-ventilated. In the warmer months, staying comfortable indoors requires cooling, and that’s when the AC part of your HVAC system becomes important. However, like any part of your home, your air conditioning system can develop problems over time.

Hissing Noises Are Coming from the Air Conditioner

If it sounds like there’s a large reptile living in your air conditioning system, you may have a leak. That hiss is the movement of air. Seventy percent of homes have leaky HVAC ducts. The hissing noise may also come from a leak in another part of the air conditioning system, such as a valve. To determine whether the system has a leak, place a stick of incense or a thin piece of paper near duct connections. If it blows around, your system is leaking. While small leaks may be fixed with foil tape, for system-wide problems it’s best to call in a professional.

My Air Conditioner is Screaming

If you hear a screaming noise coming from your air conditioning system, it’s time to turn it off and call the professionals. While the high-pressure limit switch should shut the system down if it reaches dangerous pressure levels, this safety mechanism can fail. You may also hear a screaming noise if metal is moving against other parts of the system, such as failed motor bearings. In either case, it’s best to call a professional if your air conditioning system is making a screaming sound.

The Musical Air Conditioner: Whistling, Singing, and Humming Noises

If your air conditioning system whistles as it works, this noise may be caused by air leaks in the supply or return air ducts that help move the air from place to place. Whistling can also indicate that debris is clogging the air filter.

Vibrations between metal parts, such as the fan blade and the motor, can cause your air conditioner to sing. So can a broken part, such as a broken cooling fan.

Debris clogging the system can lead to humming noises. If you find that the fins of the fan on the system are clogged or bent, you can turn off the unit and gently vacuum the fins to clean them. To help prevent clogging, keep two feet of space between your condenser and any plant material, and schedule an annual cleaning of the entire system. Humming noises can also be caused by simple problem, such as a loose screw. Inspect all of the visible parts of your system to make sure that screws are tight, and if they are not, turn them. This may stop your humming problem.

The Air Conditioner Makes Noises When It Is Starting

Some air conditioning systems make a squealing noise as they start up. Wait for a few minutes to see if the noise continues. If the noise continues or if the air conditioning system has not done this before, it may be a sign that your system is getting old and needs to be repaired or replaced.

An HVAC system is supposed to make your life more comfortable, but a noisy system can do the opposite. Have regular maintenance performed on your system to ensure it continues its quiet, essential job: making your home environment a pleasant one.