iMac: Fans run at full speed after computer turns on
Products Affected
iMac (17-inch, Late 2006 CD), iMac (17-inch, Late 2006), iMac (20-inch Late 2006), iMac (20-inch, Early 2008), iMac (20-inch, Early 2009), iMac (20-inch, Mid 2007), iMac (20-inch, Mid 2009), iMac (21.5-inch, Late 2009), iMac (21.5-inch, Mid 2010), iMac (21.5-inch, Mid 2011), iMac (24-inch Mid 2007), iMac (24-inch, Early 2009), iMac (24-inch, Late 2006), iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), iMac (27-inch, Mid 2011), iMac (Early 2006 17-inch), iMac (Early 2006 20-inch)
Symptoms
After plugging in the iMac and turning it on, the fans (blowers) may be noisy and appear to run at full speed. In this event, shutting the iMac off and turning it on again wouldn't fix the issue.
Resolution
If you press the iMac power button while you are inserting the power cord, the iMac will enter a mode in which the fans (blowers) run at full speed. In order to correct the issue, reset the SMC and then start the computer by pressing the power button after the power cord has been fully inserted.
The iMac should now start up and operate as expected.
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