Like a computer, the CPU in your PlayStation 3 game console needs a fan to cool it down. This fan is regulated by an internal heat sensor. If the fan in your PS3 is behaving erratically, like turning on more than usual, the heat sensor is likely obstructed or not functioning properly. In this instance, there are things you can do to adjust the console and hopefully fix the problem with the sensor.
Turn off the PS3 and allow it to cool.
Place the PS3 in an area where it has at least eight inches clear on all sides. This will ensure proper ventilation while the unit is on.
Use a cloth to clean the vents on the rear of the PS3 to ensure they aren't clogged.
Turn your PS3 back on. If the unit is still overheating or behaving erratically you may need to completely replace the heat sensors. To do this proceed to the next step.
Turn off your PS3 and unplug all cables from the device.
Use the tip of your screwdriver to pop the rubber cap off of the screw located near the top of the left side of the unit.
Slide the top case to the left and lift it up to remove it.
Remove the seven screws on the metal panel on top of the PS3.
Lift the panel up to expose the internal components of the PS3.
Remove all screws from the sides and corners of the square disc drive assembly and lift the drive up. Unplug the ribbon cable from the rear of the drive and remove the drive from the unit.
Remove all screws from the metal plate over the motherboard. Remove the plate.
Remove the motherboard from the lower half of the PS3 housing. The fan and cooling system are located on the top of the motherboard.
Remove all screws from the fan assembly and remove the fan assembly to expose the two heat sensors underneath.
Remove all screws over the sensors and remove the metal brackets covering the sensors.
Remove the sensors and set them aside.
Fit two new sensors over the motherboard and replace the screws and brackets.
Reassemble the PS3 in the reverse order you disassembled it.