Huey52

iTrader: (2)

Debris on the fan blades is most often the noise culprit, followed by a clogged filter.

They probably don't use large blade, slow rpm, ball bearing fans tho', which is the ideal way to move a large volume of air with low noise.

As already cited, today's A/C refrigerants are not as efficient as the old, now banned, chlorofluorocarbon based and therefore greater airflow is necessary (but still not as cold).