Apple Support - Malwarebytes and Cleanmymac

As far as I know, neither Apple, Apple Support, nor we, your fellow users, have any contract with Malwarebytes. It remains the Go To recommended application by myself, and peers in the support communities because it just works. It is also readily removeable from its Help menu.

Each new download of Malwarebytes comes with a 14-day trial of its "real-time" ad/malware detection engine, that stops working after the trial period, and is what a subscription re-activates. The downside of this "real-time" feature is that Malwarebytes elevates the run priority of that "real-time" protection engine process above all other running processes except the UNIX kernel. There is no user means to de-activate that engine prior to the end of the trial period, other than uninstalling the application. If there is anything else on your iMac that might be slowing it down (e.g. Fusion drive, or anti-virus software) then Malwarebytes trial will magnify that effect.

Generally, we have been saying for years to avoid installing any anti-virus, memory management, or cleaner category applications because they have been known to generate posts here from users who have had problems traced to their usage. If a vendor, and in your example, CleanMyMac is accepted into the Mac App Store, it is because they followed all of Apple's criterion to achieve that status. Neither we, nor Apple support are part of that vetting process, so I cannot comment further on it. Just because an application is in the Mac App Store, does not mean that it is harmless, nor that Apple could remove it from the store.

Have you replaced the drive in your iMac prior to the fan noises? We have experience with those that have replaced the iMac hard drive, and not used, or connected the heat sensor cable that would allow the Mac to regulate its thermal properties. A racing fan is the result. If this is not the case, then I would advise against using compressed air on the vents and instead, a small vacuum. You want to pull dust out, not push it further in.

As I mentioned, Malwarebytes will run an elevated priority process (its "realtime" component) for the first 14 days of the new installation trial, and then that process goes dormant after the trial period, and can only be restarted via an optional subscription. That does not prevent one from running Malwarebytes after the trial period has ended, and without a subscription.

You should never blow air into the bottom air intakes.

You should have shut down and vacuumed off the bottom air intakes.

Now you have most likely caused yourself a worse cooling problem by blowing the dust that was on the outside of the intake grill up into the iMac's Fan and Heat sink.

Viruses and Malware are two different things.

You do not need anti-virus software, but may benefit from an occasional malware check.

MalwareBytes is a good program, but it is best to just occasional run it manually to check for malware.

CleanMyMac is junk-ware, it will do nothing but take your money and leave you with a slow or borked macOS.

+1 den.thed is 100% correct.

• Malwarebytes is totally okay
• CleanMyMac is total garbage and can damage Mac OS.
• Third party AV apps are 100% worthless and add no additional layer of protections to Mac OS.

I don't run Malwarebytes in the background full time. I only run it occasionally if I think I might have picked up some malware or adware. Any app that runs in the background full time will be a resource hog and affect system performance.