iMac fan issues - what's going on?

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My iMac has suddenly started to run the built in cooling fan on almost a constant basis. I vacuumed the tiny vents along the bottom thoroughly. Also vacuumed the exhaust vents and there is no heat in the exhaust - just nice cool air. Sometimes it will quit running after a while and other times it puffs off and on. The other night I turned it off completely so I know it was cold by morning but as soon as I brought it up the fan started running. Other than the VERY annoying sound is there anything to worry about? Or is there some fix I can look into getting? Thanks!!!
 

chscag

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2017 27" iMac, 10.5" iPad Pro, iPhone 8, iPhone 11, iPhone 12 Mini, Numerous iPods, Monterey
How about telling us which iMac you have, year and model? And which version of OS X it's running? Most iMacs (except 2012, 2013, and the retina) have three fans: CPU, Hard Drive, and Optical Drive.
 
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It is:
OS X Yosemite
Version 10.10.2
21.5" late 2012
Proc is 2.7GHZ Intel Core 15
 

chscag

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Your iMac only has one central fan which provides cooling for the entire machine. The rotating speed of that fan should be around 1200 RPM at startup under normal operating conditions. Did you buy Apple care for your iMac? In any event, I would take it on in to an Apple store genius bar (make an appointment first) and have them diagnosis it. A defective temperature sensor could cause the fan to ramp up or there may be a cooling problem internally.
 
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No I did not purchase Apple Care as I don't normally buy extended warranties - oh well - We do not have an Apple Store here in town, but I bought it at Best Buy and they imply they are authorized to work on Apple products - guess I better go there. BTW the fan has now stopped running and may not run again for some time.
 
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Just while I have your attention why is the time on these threads always hours off? Like now this conversation is supposedly at 11 PM tonight which is 6 hours from now.
 

pigoo3

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...but I bought it at Best Buy and they imply they are authorized to work on Apple products - guess I better go there.

A humorous why of putting it…"imply"!;)lol

Yes Best Buy is "authorized" to work on Apple products. But many of us here at Mac-Forums simply question IF THEY SHOULD be working on Apple products!!!;)

I could "imply" that I could work on a NASA rocket! But I probably shouldn't!!!lol;)

- Nick
 

pigoo3

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Just while I have your attention why is the time on these threads always hours off? Like now this conversation is supposedly at 11 PM tonight which is 6 hours from now.

Maybe your time zone is not correctly set in your Mac-Forums settings.

- Nick
 
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Maybe your time zone is not correctly set in your Mac-Forums settings.

- Nick

Where do I find that? All I found was the statement that "All times are GMT" and that it is 6 hours later there than here!
 
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A humorous why of putting it…"imply"!;)lol

Yes Best Buy is "authorized" to work on Apple products. But many of us here at Mac-Forums simply question IF THEY SHOULD be working on Apple products!!!;)

I could "imply" that I could work on a NASA rocket! But I probably shouldn't!!!lol;)

Hey - don't you trust the Geek Guys - ;)

BUT (and still learning!) - would resetting SMC & PRAM be worth a try (as explained HERE)?

About a year ago, wife came running out of the computer room complaining about her iMac's fan was WHIRLING! - I reset one or the other (maybe both) - corrected the problem and not an issue since that time - just wondering. Thanks - Dave
 

pigoo3

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Where do I find that? All I found was the statement that "All times are GMT" and that it is 6 hours later there than here!

Check all the settings in your profile. There's a time zone setting there.:)

- Nick
 
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My 2009 iMac had the same problem.... constant fan running. Turns out it was a temperature sensor that needed to be replaced. I wouldn't trust Best Buy for any computer repair, but that's just me. Good luck!
 

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