It is possible that the SMC could face problems that can cause unusual system behavior typically related to the symptoms described below. In some cases, resetting the SMC may be the only correct method to resolve the issue, however, SMC reset should only be attempted after all other standard issues have been conducted.
Fan / fan rotates rapidly and with high speed.
Fan / computer fan running at high speed even though the computer is not experiencing heavy use and well ventilated.
Keyboard backlight appears to behave correctly (on Mac computers that have this feature).
Status Indicator Light (SIL) appears to behave incorrectly (on Mac computers that have a SIL).
Battery indicator lights, if any, appear to behave incorrectly (on a portable that uses a non-removable battery).
The backlight of the screen does not respond properly to environmental light changes on Mac computers that have this feature.
Computer does not respond when the power button is pressed.
Computers do not respond properly when you close or open the lid.
Computer sudden sleep or shut down by itself.
Battery not charging process correctly.
The MagSafe power adapter LED does not appear to indicate charging activity right.
This computer is running extremely slow despite not experiencing abnormally high CPU utilization.
A computer that supports target the display mode is not switched into or out of target display mode as expected. A computer that supports the display mode to target into or out of target display mode at unexpected times.
Try each of the following steps in this order before you reset the SMC on mac. Test the issue after completing each problem step to determine whether the problem still occurs.
Press Command + Option + Escape (Force Quit) to exit the coerce any application that is not responding.
Put your Mac on the position of sleep by choosing the Apple menu top left of the menu bar and then select Sleep. then wake it back on when the position of sleep.
Restart your Mac by by choosing the Apple menu top left of the menu bar and then select Restart.
Shut down your Mac by by choosing the Apple menu top left of the menu bar and then select Shut Down.
If your Mac appears to be running normally but is not responding, force the computer to shut down by pressing and holding the power button for 10 seconds.
Note: You will lose unsaved work in open applications.
Mac Shutdown. Physically remove and replace the battery (if it's removable) and startup the Mac.
If the problem is still not resolved after following the troubleshooting items above, resetting the SMC may be required.
Turn off the Macbook / Shut down.
Disconnect the MagSafe power adapter from the computer, if connected.
Connect / replace the battery and MagSafe power adapter.
Note: Portable computers that have a battery you should not remove batree eg in MacBook Pro (Early 2009) and later, all models of MacBook Air, and MacBook (Late 2009).
Connect / Plug in the MagSafe power adapter to a power source, if not already connected.
On the keyboard, press (left) Shift-Control-Option keys and the power button at the same time.
Remove all keys (Shift-Control-Option) and the power button at the same time.