Window air conditioners provide targeted cooling to small rooms and are ideal for apartments and small homes. However, over time, they can become noisy to the point of being disruptive, for a variety of reasons ranging from age to actual damage. If your window air conditioner has become particularly noisy, there are a number of things you can look at to attempt to identify and solve the problem.
Noisy operation within a window air conditioner is often because of fan blades which have become bent out of shape, hitting the interior of the unit or causing the entire air conditioner to become unbalanced. Take the covering off of the air conditioner and inspect the blades to see if they are bent out of shape. If they are, you can attempt to straighten them either with your hands or a pair of pliers, but it's always best to contact a professional to ensure that you do not damage the blades further.
If debris, such as leaves or other items, have become lodged within your air conditioner, they can adversely affect the function of the unit. They can cause permanent damage to your air conditioner if they are not removed immediately. Simply remove the front covering of the unit and inspect the interior to see if there are any foreign items inside. If there are, simply cleaning them out can silence your noisy air conditioner. If there isn't anything inside, your air conditioner is most likely making noise for another reason.
A window air conditioner has a grill on its front that protects the air filter within the unit. If the grill is installed loosely, or if the lock on it has become damaged in some way, it may be rattling while the air conditioner is in use. Remove the grill and put it back on the air conditioner tightly. If the locking mechanism or the grill is damaged and won't sit on the unit properly, you'll have to contact a professional to either repair or replace the unit.
If your air conditioner's noise is continuing despite checking the above possibilities, your fan motor may not have enough lubrication to continue working properly. If this is the case, you'll need to refrain from using your air conditioner as much as possible to prevent damaging the motor. Contact a professional to inspect and add more lubricant to your air conditioner as needed.
For more information on air conditioner maintenance, check out websites like http://www.nathansheatandair.com/.