My Air Conditioning Is Too Loud!

    Photo: michael_swan/Flickr

    Whether you live in Manhattan or suburban Tulsa, air conditioning  that's too loud provides equal parts comfort and annoyance. NYC's Noise Code legally limits how much racket an AC can make: 42 decibels, measured at a distance of 3 feet from the unit. That's about halfway between a whisper and normal conversation. Or you can think of it as two people having a friendly chat on your fire escape while you're inside, trying to sleep. And that's the expected noise level when the equipment is working properly; a unit with a problem might be much louder -- more like those people on the fire escape having a heated argument, or maybe conducting a yodeling class.  So, wudya gonna do abat it? (That's for the New Yorkers.)

    Where to Start

    If your air conditioning is too loud, the first question to ask is: Has it always been too loud or has it recently gotten a lot louder? The answer helps determine which road to take toward solving, or at least minimizing, the problem. If your air conditioning has always been too loud for your liking, you'll need to consider some basic noise-mitigation solutions. On the other hand, if your AC has normally been tolerable but now seems a lot worse, it has a mechanical problem that needs fixing, so you're headed down the ol' repair path (bring your wallet).

    Noise Mitigation

    The noisiest part of most air conditioners is the compressor. In a central AC system, the compressor is a large, rounded cylinder located in the outdoor unit, underneath the fan that you can see through the top grille. The second-noisiest part is the fan. Newer AC units have relatively quiet fans so most of the noise comes from the compressor. With older models, once you quiet the compressor you realize how loud the fan is and unfortunately, there's no great fix for this other than buying a new outdoor unit.

    1. The simplest way to quiet a compressor is by insulating its housing with a special soundproofing blanket specifically for this application. Don't try a DIY jury-rig here; buy the real thing and install it precisely as directed. You can take care of the installation yourself, but consider this option only if you're comfortable working with high-voltage appliances (see A Quiet Discussion About Safety, below). Compressors are cooled internally, so insulating their housings typically does not create a problem with overheating, but it's a good idea to check with your unit's manufacturer to make sure a sound blanket won't void any part of your warranty.

    2. Another solution for central air conditioning that's too loud: add anti-vibration pads to the outdoor unit. These durable, inexpensive rubber pads slip right under the feet of the unit, reducing vibration between it and the concrete slab below (or whatever surface your AC is standing on); install as directed.

    3. A more expensive option is having a "soft start" controller installed on the unit. This electronic device reduces the startup current (the blast of electrical power) required to start the compressor, thus reducing the noise (and possibly flickering lights, if you have that problem) of startup.

    4. Finally, you can move the outdoor unit to a place where noise isn’t so disruptive, but since that's rarely practical you might consider a small fence or similar barrier to deflect noise away from the house. The main concern here is leaving adequate space around the AC unit for air circulation; three feet is a standard minimum clearance.

    5. Options for quieting a window air conditioner that's too loud are not as promising. While you can find covers to prevent outdoor sound from coming through the units (during the off season), there aren't blankets for muffling those noisy little compressors. So focus on making sure the fan is clean and running smoothly (see below) and that the mounting system is not causing any unnecessary noise from vibration, loose fasteners or parts rubbing together. Failing that, a new unit is your best bet. Don't trust manufacturer's claims implicitly; check Consumer Reports and user reviews to make sure the new model is truly quiet.

    Likely Mechanical Problems

    The components that make air conditioning too loud when units are operating properly are usually the same things that cause sudden increases in noise. We're talking, of course, about the compressor and fan. Compressors are motors and can get noisier with age. You can try quieting an old compressor with a sound blanket, as described above, and live with it until the compressor dies. Or, you can find an HVAC pro to check it out and decide whether replacement (of the compressor or entire unit) is the better approach.

    Fans can become noisy from dirty blades, loose or bent blades, or worn bearings. Dirty blades are easily cleaned, and loose or bent blades, which often create noise by rubbing against other parts, can simply be tightened or straightened out. However, worn bearings typically lead to replacing the fan motor, as most units have factory-sealed bearings that can't be lubricated again once they run dry.

    A Quiet Discussion About Safety

    When it comes to DIY repair work, air conditioners are nothing like, say, toilets. Any schlub who can handle a pair of pliers is capable of fixing pretty much any problem on a toilet and should be encouraged to do so. Air conditioners are a different story. While mechanically inclined amateurs can perform a number of maintenance jobs on both window and central AC units, those who don't have a solid grasp of the power system and refrigerant components of an air conditioner are strongly advised to call a pro for any repairs or internal inspections.

    For one thing, AC units, like a lot of motorized equipment, have capacitors that store potentially dangerous amounts of electricity -- even when the power is completely shut off. HVAC pros routinely discharge capacitors using tools as simple as insulated screwdrivers. But they know what they're doing. If you're poking around inside an AC cabinet, you could accidentally discharge a capacitor into your body. Not cool, in any sense of the word. 

    Philip Schmidt writes for

    Updated March 20, 2018.

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