Instructions
Turn off the PS3 by flipping the power switch on the back of console to the "Off" position. Do not turn it off by hitting the "Power" button on the front of the console; that just puts it on standby.
Flip the power switch to the "On" position and press the "Eject" button at the exact same time. The "Eject" button is located directly in front of the disc slot on the front of the console.
Hold down the "Eject" button until the fans begin to spin fast. It will be loud. Let go of the button and let the cleaning complete. Self-cleaning takes 10 seconds. Once this is complete, the PS3 will be in standby mode.