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Older iMac Beeping

K

krawfo

macrumors regular
Original poster
May 4, 2011
193
11
I have an older (2011) 27" iMac that I don't use much and it stays in sleep mode. A couple of days ago I noticed a very loud fan noise and a blank screen. I powered the machine off by pulling the plug and let it sit for a couple of days. Today I powered it up and it started to beep about once every 3-4 seconds. Eventually it booted up normally and I was able to access the internet via Chrome though the beeping continued. The loud fan was not evident either but I only let it run for about 5 mins.
Any guesses as to what might be going on or diagnostics I could run?
Thanks.
 
I'd try removing and re-seating the RAM (door on the back).

If you "don't use it much", my advice would be to shut it down when not in use, rather than "sleep it".
 
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Fishrrman​

Thanks for the reply. Took all the RAM out and re-seated it - still beeping. Right now I'm running the diagnostics triggered by holding down the D key at startup. SLLLOOOW ! Will report the results when finished.
 
The plot thickens ... Hardware test reports error 4SNS/ 1 / 40000000: T H 00 - 9.000
Looks like this is a HDD fan error message. The loud fan noise I mentioned in my initial post returned during the test.
About 7-8 yrs ago I added an SSD to this machine and (if I'm remembering correctly) plugged the HDD into the CD-ROM controller. I just downloaded and installed Macs Fan Control. I set the HDD fan speed to Based on Ambient and the fan is now nearly silent and the beep is gone.
Is my problem fixed or do I need to do something else?
 
That's interesting. I don't think I've ever run across a Mac beeping because of a defective HDD temperature sensor that sent the fan into high rpm. Macs Fan Control is a great app that can take care of those kind of problems. I also have it installed on my iMac. If the beeping stopped, I believe your problem is fixed.
 
Since you have a 2011 27" iMac, removing the screen to get to the HDD fan would be a fairly simple procedure. It is possible that accumulation of dust, or a worn out fan prevented the fan from spinning resulting in the "beeps"? Give it a good dusting out with an air can and do a visual on the fan. Ifixit.com has good directions on removing the screen...
 
OP:
"I just downloaded and installed Macs Fan Control. I set the HDD fan speed to Based on Ambient and the fan is now nearly silent and the beep is gone.
Is my problem fixed or do I need to do something else?"

Well, if the "beep is gone", it sounds "fixed" to me. At least for now.

Again I will make the suggestion:
If you use this iMac only occasionally, the best practice might be to SHUT IT DOWN between uses. No need to leave it on.
 
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