I have a 1 year old iMac running Big Sur 11.3. The last couple of days the fan is coming on from time to time. It's never come on before and I'm not doing anything different on the computer than I ever have. The fan issue seems to correlate with the most recent OS update. I've turned off and unplugged the iMac and then restarted and no change. Any suggestions?
iMac 27″, macOS 11.3
Hi Imaceaf,
See if these articles help;
Cheers,
Jack
Hi Imaceaf,
See if these articles help;
Cheers,
Jack
Can you clarify something? Was the fan quiet when you were running earlier versions of Big Sur OS11?
If Jack-19's well-chosen links do not help...
Intermittent speeding up of the fan (it is "on" all the time but at low speed) is a response to heat inside the computer. That means the computer is either working harder or something is blocking the air intake or exhaust vent.
Useless third-party utilities like anti-virus and so-called "cleaning" apps can rnu up temps and, because thise developers always seem to be "behind the OS curve" can work poorly after an incremental update like 11.2 >11.3. If the useless-ware is not rthe update, it can cause issues.
As for venting, your iMac has its intake ports on the bottom edge of the case:
and the exhaust port is inconveniently placed under the point where the stand attaches:
Thought testing I have found the stacking ANYTHING between the desk and the intake ventss cans start to run up temps. Likewise, tipping the display full-forward reduces the space in front of the exhaust port and not enough hot air can be ejected. Temps go up.
So if reseting the SMC changes nothing, and you get an error-free Diagnostic report, first check that your vents are clean and clear of desktop items. Make sure the display is not tipped fully forward. Then determine it you have installed anti-virus or cleaning apps and evict those with extreme prejudice--they are hurting, not helping.
That's good for now. Looking forward to your followup.
Please reset the SMC 2 to 3 times with all external wired peripherals disconnected period then restart and test
Fan Running on iMac
