Why is my Mac fan so loud and how to fix it?

Yeah—- Don’t do that, not necessary and will void your warranty ( probably even with AppleCare + ) … you can use Activity Monitor to see what application/piece of software is hogging cpu time or has gone a bit funny, and force quit it ( yes, even the Finder) … if that doesn’t help regularly, you might want to get and use “EtreCheck” for a more detailed overall report

john B

If your iMac is running macOS 10.15 as indicated in you equipment line, then it is one of the "thin-case" models that you do NOT want to open. If hat is not that iMac, please tell us which you have.

Before doing anything else, check your workstation. Make sure NOTHING is between the bottom edge of your iMac's body and the work surface. That gap of roughly 2-3/4 inches between the lower edge of the body and the work surface MUST be maintained:

This image was posted here by a user who also had also had severe overheating issues that cause the fan to run at full speed:

That significant blockage of the intake vents is what we call a "self-inflicted wound." When he removed the junk, the temps normalized.

If you have the iMac set high above your eye line and must tip the display fully down to use it, that can overheat the device as well. In the fully tipped-down position, the important hot air exhaust vent is significantly occluded by the upper part of the stand. I can reproduce that overheating at will on my 2017 iMac:

Obviously, you want to make sure the intake vents are not clogged with dust.

Reset the SMC 3 or 4 times in a row and see if this helps

Reset the SMC of your Mac - Apple Support

Mal-S wrote:

Reset the SMC 3 or 4 times in a row and see if this helps

Reset the SMC of your Mac - Apple Support

Please identify the model year iMac that you own, if you don't know click the  symbol in the upper left of the display and then click About this Mac and you will find the information requested.

Based on what you post we can provide some advice on what to do.

hello. i tried every possible way to fix the fan max problem.. what do you mean by in a row...

1) Power off -> unplug -> 15sec -> plug : doing this in a row

2) Power off -> unplug -> 15sec -> plug -> 5sec -> Power On. : doing this in a row

Also try running the Apple Diagnostics to see if any hardware issues are detected.

You may also want to disconnect all external devices in case one of them is causing a problem.