Fixing Noise Issues With A Window AC Unit

Posted on: 15 January 2016


Not all homes are lucky enough to have central air conditioning, as some still use window units. Usually, these units work quite well if they are sized appropriately and properly maintained. Occasionally you may have issues with a loud window unit. The following guide can help you discover the cause of the problem.

Ongoing Vibration Noises

These noises are ongoing any time the unit is running, although they may get more intense at higher fan settings. The noises can usually be traced to where the housing rests on the window sill and not to the motor and fan compartment. To solve the issue, first and foremost make sure the unit is properly supported where it hangs outside of your window. You can build or purchase premade platforms that can be installed on the sill to further support the AC. Then, to minimize the vibrations on the frame, install a foam strip between the unit and the window frame to create a sound and vibration absorbing buffer. You can purchase plain foam weatherstripping to use for this purpose, or there is specially made foam tape available just for this purpose.

High Pitched Squeals

This is typically a lubrication problem. The most common culprit is the fan motor inside the unit. In some cases, you can access the fan and apply a few drops of a silicone lubricant to the point that spins on the axis. Just make sure the unit is off and unplugged before removing the cover. Some units have the fan motor inside a sealed box. In this case, you will need need an HVAC repair technician to open the sealed motor and lubricate it properly.

Rattling Noise, Front of Unit

The front of the unit is the part that is inside your home. You should be opening it up monthly and removing the filters for cleaning or replacement. Rattling or slow vibration noises may occur at this location for several reasons. Most common is that the filters or front grill isn't replaced properly, so you can hear them rattling around. Another issues is that something may have fallen into the front of the unit, perhaps when you were cleaning the filters. With the unit off and unplugged, vacuum out the filter slots with your shop vacuum. This should remove any foreign objects.

Rattling Noise, Rear of Unit

This is usually caused when objects fall into the motor and fan housing, perhaps through the vents on the rear of the unit. Turn off and unplug the unit, and then remove the back cover from your AC. You will probably need to remove some screws in order to do so. Next, vacuum out any foreign objects with your shop vac. Once done, you can reassemble and turn the unit back on.

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