How to Reduce Air Conditioner Noise

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While air conditioning can make life more comfortable in the hot summer months, they can be noisy whether they are window-mount air conditioners or central air. A few simple fixes can provide you with comfortable temperatures and low noise. This article w

While air conditioning can make life more comfortable in the hot summer months, they can be noisy whether they are window-mount air conditioners or central air. A few simple fixes can provide you with comfortable temperatures and low noise.

Window Air Conditioner Repairs

Check the Fit in the Window

If you leave your window air conditioner mounted year-round, there is a good chance that the mounting bracket has loosened around the air conditioner. Check to see if any bolts or screws are loose or missing. With a flashlight, inspect the underside of the AC and look for gaps around the frame. With the unit running, place a paper or plastic cup on top of if the frame is vibrating. It is possible that the noise is coming from the inside of the unit. If the mounting bracket is screwed in through the siding, replace with larger screws or lag bolts. Make sure that the fasteners are in the framing and not just secured to the sheathing.

Check for any soft or rotted wood around the window unit. If the AC has been left in place for several years condensate may have entered the wood framing and caused it to rot. Without the proper support the unit may have shifted and caused it to vibrate. You would need to remove the AC unit and repair any rotted or damaged wood. Make sure that the flashing is installed properly around the unit to prevent future water damage.

Seal around the unit with new weatherstripping or caulk. Some units come with rubber washers or bushings that are installed under the unit. Inspect to make sure that they are in place.

Check the Front Panel

Sounds could also be caused by a loose front panel. This is an easy fix and simply involves tightening the screws or checking to see if the clips are securely in place. If there are broken or missing clips, you can try some adhesive weatherstripping or double-sided tape to dampen the sounds or hold the panel in place.

Check the Compressor mount

When window air conditioners are shipped, they often include special clips or over tighten the mounting bolts to secure the compressor during shipping. Remove the front or side panel to see if any packing clips or supports are in place and check that the compressor bolts are just snug. Use an adjustable wrench to loosen them if necessary.

Check the Fan Blade and Motor

Dirt can cause the fan blade to become unbalanced. Clean the fan blades with a damp rag. If the blade is still noisy check to see if there are any oil ports to lubricate the motor and bearings. Look for caps covering the oil ports and add a few drops of oil to each port. Add a couple of drops of oil along the motor shaft and manually rotate the fan to spread the oil.

Check the Compressor Operation

After several years the compressor will get progressively louder and it is cost prohibitive to repair or replace the compressor. If the compressor is so loud it shakes the entire unit, shut off the AC and look for a replacement window air conditioner.

Check the Coils

Occasionally the fins on the exterior section of the AC unit can become clogged with debris or damaged that can cause a humming sound. Remove the unit from the window and clean the condenser coils with a vacuum and soft brush attachment. You can also try using a chemical coil cleaner and water to remove any dirt. Check to see that the fins are straight and align any bent fins with a coil comb. Small leaves or paper can become stuck in the coil and cause a buzzing sound.

Central Air Conditioning Condenser Units

Condensing units are located outside to discharge the heat from inside the home. They consist of a compressor, the condenser coil, and a fan. Noisy can be caused by a bad fan motor, a worn out compressor, the coil being clogged with debris, or the unit not being set level. In most cases the noisy is from a worn out fan or a noisy compressor; on older units you may need to lubricate the condenser fan, or replace it if the bearings are worn out.

For noisy compressors you may want to purchase a sound blanket that fits around the compressor to dampen the noise.

The use of a sound blanket will not adversely affect the compressor's performance and sound blankets are often used by manufacturers to reduce noise levels. Sound blankets can come in one and two-piece designs depending on the brand and the size of the compressor. Two-piece blankets are a good option where the compressor is close to the coil or the fan. The sound blanket is securely attached with hook and loop closures so it can be removed easily if repairs are needed.

On newer condensers, the fans are relatively quiet, so the compressor is still the loudest component in the unit.


Contact the manufacturer to find a sound blanket for your model or buy a universal blanket from an online seller. Prices range from $40 to $70. If your condenser unit is over ten years old, you might want to consider installing a new high efficiency unit. The payback period is usually 3 to 5 years.

Shut off the power to the condenser unit using the service disconnect mounted on or near the unit.

Unscrew and lift off the top panel where the fan and motor is mounted; you may need help for this part. Use a nut driver or screwdriver to remove the screws in the panel. Place the sound blanket around the compressor and secure it in place.


Regina Peterson
Posted on Mar 13, 2015
Patrick Regoniel
Posted on Jun 20, 2012
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