Fan Test
By using a combination of button presses and flipping the rear power switch, the cooling fans spin at increasingly rapid speeds for about 20 seconds. Sony suggested this speed in an official test designed to test functional operation of the cooling fans. The claim is that the unusually fast fan rotation blows any accumulated dust from the system. The procedure has since been called a "self-cleaning feature." It is only available on the 40 gigabyte model PS3.
Officially Unofficial
There has been no official word from Sony regarding this test, though some gaming forums claim Sony has advised not to perform the test. There is a belief that the test was built into certain models of the PlayStation 3 for Sony employees and official repair sites to trouble shoot overheating and power issues, though there is no information in the Sony owner's manuals regarding the test.
Problems
There a unofficial reports on gaming forums, including Sony's own community forums, suggesting the company has warned against this procedure. Problems have been identified in attempting the procedure with any model other than a 40 gigabyte model because the methods used to recreate the test with other models involve turning the system upside down while the system is on and the fans are running. This causes heat to be trapped inside the system and can damage the sensitive electronic components inside since the vents are on the top of the unit.
Not for Amateurs
Official information is scarce regarding the supposed self-cleaning feature of the 40-gigabyte. This and the fact that it is not mentioned in any of the user manuals or trouble shooting tutorials indicates that, at the very least the procedure is not meant to be performed by anyone other than professionals trained to repair the consoles. Additionally, Sony's own online community forums indicated many users have had problems and even permanently damaged their PlayStation systems by attempting to perform the self-cleaning feature.