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User profile for user: dinosaur56
dinosaur56 Author
User level: Level 1
1 points

My iMAC's cooling fan started up and won't shut off. What can I do?'t ever stop.

I recently had a situation where an application(Stuffit Expander) got stuck trying to expand a RAR download. I couldn't quit Stuffit expander, and was being blocked from putting the computer to sleep or shutting down, so I had to unplug the iMAC from electricity. When I plugged it back in, I couldn't get the iMAC to power up, so I simultaneously plugged in to electricity, and pushed the button on the back of the computer. Now the computer is working again, but the cooling fan runs at all times, and even after Apple Care put me through steps to reset the computer, the cooling fan drones on and on and on. Though I'm in South Florida where the weather is often warm(though not today), I'm operating the computer in an air conditioned room. The computer is not overheating.


I hate the idea of taking the computer in for repair and having to do without a computer(I've owned this iMAC for less than 2 weeks). My previous iMAC(a 2007 unit which has power supply problems was too costly to repair at the Apple Store, though I may eventually take it to an independant repair shop.)

iMac, Mac OS X (10.7.2)

Posted on Jan 22, 2012 9:56 AM

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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
140,346 points

Posted on Jan 22, 2012 9:58 AM

Try doing a SMC reset, it may take 2-3 attemps for it to work.


SMC RESET


  • Shut down the computer.
  • Unplug the computer's power cord and all peripherals.
  • Wait 15 seconds.
  • Attach the computers power cable.
  • Wait another 5 seconds and press the power button to turn on the computer.



PRAM RESET


  • Shut down the computer.
  • Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  • Turn on the computer.
  • Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
  • Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  • Release the keys.
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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
140,346 points

Jan 22, 2012 9:58 AM in response to dinosaur56

Try doing a SMC reset, it may take 2-3 attemps for it to work.


SMC RESET


  • Shut down the computer.
  • Unplug the computer's power cord and all peripherals.
  • Wait 15 seconds.
  • Attach the computers power cable.
  • Wait another 5 seconds and press the power button to turn on the computer.



PRAM RESET


  • Shut down the computer.
  • Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  • Turn on the computer.
  • Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
  • Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  • Release the keys.
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User profile for user: den.thed
den.thed
User level: Level 9
76,978 points

Jan 22, 2012 10:02 AM in response to dinosaur56

Your system management controller is wacked out from that maneuver and you need to reset the SMC > Intel-based Macs: Resetting the System Management Controller (SMC)


1. Shut down the computer.

2. Unplug the computer's power cord.

3. Wait fifteen seconds.

4. Attach the computer's power cord.

5. Wait five seconds, then press the power button to turn on the computer.

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User profile for user: Simon Rioux
Simon Rioux
User level: Level 1
24 points

Oct 11, 2013 1:05 PM in response to dinosaur56

The SMC and PRAM resets did not work at all for me. I used smcFan utility to find out that the temperature of my CPU was actually quite high, so it wasn't a software defect that was making the fan turn so fast (like this thread is saying).


I have a 2007 iMac, and the inside was just dirty enough to stop hot air from coming out properly. I had it cleaned up by a technician, and all is well now. Yes, after 6 years of working 24/7 as a workhorse, my iMac needed a little clean-up, yet my house is very clean. Just normal use I guess... I've never had a computer that lasted so long, so I didn't know that cleaning a computer is normal - until now!


I had previously opened my iMac on several occasions to upgrade my HDD, try out an SSD, and it was clean inside. Except at the hot air exit it seems, located above the power plug outlet on the back of the machine. It was a wee bit whitish... 🙂

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User profile for user: Adventure994
Adventure994
User level: Level 1
4 points

Jan 15, 2014 5:50 PM in response to dinosaur56

Phone support could not solve the problem. I took it to a retail store where they did the SMC reset which seemed to work; then they ran hardware diaganostics and all the hardware seemed to check out. Then next day the problem returned. I tried the SMC and PRAM resets several times myself to no avail.


Another call to tech support and they recommended to reinstall the OS which thankfully is a fairly painless process. But that did not solve the problem either. The fan still comes on full blast upon shut down and remain on until I depress the power button on the back of the machine at which time the machine restarts. There is no way to get it to shut down without the fan coming on full blast without unplugging the power cord.


Back to tech support...

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My iMAC's cooling fan started up and won't shut off. What can I do?'t ever stop.

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