Indicator Lights
The PS3 console has three LED indicators on it: the main LED near the power button, the hard drive disk access indicator to the right of the front USB ports, and the Wi-Fi LED to the right of the HDD access indicator. Older versions of the PS3 had additional lights near the power button that showed the disk status. The HDD access indicator is a yellow light that blinks when the hard drive is in use, and the Wi-Fi LED is a green light that turns on to indicate that the PS3 is connected to a wireless network. Under normal circumstances the main LED turns solid green, blinking green or solid red, depending on the console's status.
Red LED Indicator
If the main LED on your PS3 is red without flashing, that's normal. The system is off and the PS3 isn't indicating a problem. If the LED is flashing red and the PS3 won't turn on, your PS3 is encountering some type of serious error, perhaps from overheating. If the PS3 won't turn on after you've let it cool off for 30 minutes to an hour, contact Sony support (us.playstation.com) to see what your options are for servicing.
Other Warning LEDs
The most common warning indicator you may see is the main LED alternating from red to green while the system is on. This means the console is beginning to overheat, and you should save your progress in any open games and turn off the PS3 as quickly as possible. Another error indicator is the LED changing from green to yellow to green to flashing red. This is a sign of a serious error in the system, and the console won't turn on. Contact Sony about getting the unit repaired or replaced.
PS3 Maintenance
One of the most common causes of problems with modern gaming consoles is overheating. Most modern consoles work extremely hard to maintain a complex game engine and render high-definition graphics, and that work heats up the systems' components. If you properly maintain your PS3, you can reduce the possibility of overheating and experiencing game crashes or even system failures. The best way to do this is to turn off and unplug the PS3, and then clean its vents with the hose attachment of a vacuum cleaner. Don't use a compressed air can to clean the vents, since that could damage the console.