I bought this AC to replace one that was very noisy, as this one was recommended as being one of the quietest for its size. However, when I turned it on and the compressor engaged, it rattled like crazy. I quickly discovered that the air filter was causing the noise. Once I slightly disengaged it from its locked-in setting, the unit was much quieter. The fan is very quiet, and I am pleased with its cooling capacity. It also removes a tremendous amount of moisture from the air.