Mac fan won't stop, even after quitting apps
Why a Mac fan keeps running after the work is done or with the lid closed, and the checks that stop it.
Why won't my Mac fan stop?
The chip takes time to cool after heavy work, and some tasks continue in the background after the app closes. A stuck system process can also keep it busy indefinitely.
What should I check?
Activity Monitor sorted by % CPU. A system process such as mds_stores or WindowServer near the top explains it: WindowServer high CPU.
What if nothing is using CPU?
Restart the Mac. If the fan still runs at idle on a cool Mac, it needs service.
Common questions
Why does my Mac fan keep running when closed?
A background task or a wake from sleep keeps it working. Check the wake log and Activity Monitor.
How do I reset the fan on an Apple silicon Mac?
Restart. There is no separate fan or SMC reset on Apple silicon.