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Late 2009 iMac fan always full speed

deafgoose

deafgoose

macrumors regular
Original poster
Oct 20, 2011
232
4
Here are the iStats of my iMac.

istats.png



Even after turning off my iMac all night long, the fan speed will be very high after I boot up.

I have another iMac (same model) that is always quiet. WTF?

I tried using smcFanControl but it does nothing.
 
Yes I have tried SMC reset. No luck. Even when I put it in sleep mode, my fan stays on. :(

It seems to be my Optical Drive Fan that is running at 4,348 rpm.

That is what it says in smcFanControl v2.3

opticalfan.png
 
Last edited:
It could mean that optical drive thermal sensor gone bad. Run AHT in Extended mode. If I am right, you should get an error code related to this part.
 
666sheep said:
It could mean that optical drive thermal sensor gone bad. Run AHT in Extended mode. If I am right, you should get an error code related to this part.
Click to expand...

I can't run AHT.

I have a late model 2009 iMac running OS X Lion.

Apple discontinued AHT. :rolleyes:
 
simsaladimbamba said:
You could try this?

And if that doesn't work, you probably still have your Mac OS X 10.6 Snow Leopard DVDs around to run AHT.
Click to expand...

I was able to get into AHT mode using the Snow Leopard Application install DVD. The extended test was taking way too long. I will do it tonight before I go to bed and post up the results in the morning.

:)
 
Last edited:
Update:

I got a temperature sensor error after completing the AHT.

4SNS/1/C0000008: T00P--124

My iMac is out of warranty. What can I expect to pay to have it fixed by Apple?

Could I just purchase the sensor and replace it myself?

aht.jpg
 
deafgoose said:
Could I just purchase the sensor and replace it myself?
Click to expand...

If you feel comfortable to open up your iMac, then yes, it's doable. You need to remove glass and LCD. Sensor is bundled with cable AFAIK (ask seller before buying to be sure), for 21.5" you need part number 922-9214, for 27" it would be 922-9229. It costs few dozen bucks.
 
Is there software that I can use to adjust the fan speed for the optical disk drive?

I keep reading that smcFanControl is the best program but the minimum fan speed for my ODD is 4,000rpm? WTF?

smc.png
 
Last edited:
I just got back from an appointment at the Genius Bar armed with all the information I need to order the replacement sensor.

Turns out they wont let me order it. They need the serial# of my iMac and they also need to do their own test before their system will let them order the part.

This wont work because I use my iMac for my online business and cannot be without it. WTF?

So at this point, my only option is to install software to slow down this fan. The only problem is I cant find anything that has control over the ODD fan.
 
666sheep said:
I'm afraid that no software is able to control this fan when its sensor gives wrong info to the logic board (i.e. fan is working in kinda "emergency mode").

You can order part here: http://www.macpartsonline.com/imac-parts.html and replace it yourself if you feel skilled enough.
Click to expand...

Thanks but there are no sensors for sale on that website for a 21.5" iMac

http://www.macpartsonline.com/imac-parts/imac-aluminum-21-5-inch.html?type_part=105

If I can find the part, I can replace it myself no problem.

Edit: Where is the sensor located exactly? I need to figure that out before I order the parts.

These are my choices:

661-5172 - Optical Drive
922-9130 - Optical Drive Data Cable
922-9120 - Optical Fan
922-9214 - Optical Temp Sensor Cable
 
Last edited:
deafgoose said:
Thanks sheep! You have been so helpful to solve my problem. I really appreciate it.

I sent them an email asking if the temp sensor is included with the cable. :)
Click to expand...

Sorry to resurrect an old thread, but what ever came of this? I had a strange experience last night with the fans going full blast. But mine corrected by putting it to sleep, leaving it that way while I watched a movie and then when I returned and woke it up, it was fine.
 
TitanTiger said:
Sorry to resurrect an old thread, but what ever came of this? I had a strange experience last night with the fans going full blast. But mine corrected by putting it to sleep, leaving it that way while I watched a movie and then when I returned and woke it up, it was fine.
Click to expand...

I replaced the optical disk drive temp sensor cable and it solved my problem. :D
 
There are a LOT of different things that can cause the fans to go full blast, but it ultimately boils down to the system either thinking that something is overheating or the system not knowing the temperature and running the fans to be safe.

From the OP's iStat picture, it was clear that the optical drive temperature sensor was acting up, since it wasn't in the list of temperature sensors. Granted, it could still be the logic board itself not seeing the sensor correctly.
 
Not, to rekindle an old discussion, but I have a similar problem with Mountain Lion on an Early 2009 iMac.

I have iStat Menus installed and when the fans go berserk, I notice that half of the temp sensors go "missing" (they have a "-" in place of their temp). If I reset the SMC, I have a 4/5 chance that the system will return to normal for a period of time, but the sensors and fans will eventually go haywire even if I don't use the computer much.

I just reset the SMC, so I can't take a screenshot, but I'll add one the next time it happens.

Is there a way to get the hardware test to burn onto a CD? I cant find the original system disk, and I cannot get it see the supposedly online version from the apple support page.

What are people's opinions on tools like TechTool Pro, Drive Genius and the like? What happend to the TechTool Deluxe that used to be available for AppleCare?

- Adrian
 
Screenshots! (It happened again after 30 min of minimal usage..)

adriandlm said:
Not, to rekindle an old discussion, but I have a similar problem with Mountain Lion on an Early 2009 iMac.

I have iStat Menus installed and when the fans go berserk, I notice that half of the temp sensors go "missing" (they have a "-" in place of their temp). If I reset the SMC, I have a 4/5 chance that the system will return to normal for a period of time, but the sensors and fans will eventually go haywire even if I don't use the computer much.

I just reset the SMC, so I can't take a screenshot, but I'll add one the next time it happens.

Is there a way to get the hardware test to burn onto a CD? I cant find the original system disk, and I cannot get it see the supposedly online version from the apple support page.

What are people's opinions on tools like TechTool Pro, Drive Genius and the like? What happend to the TechTool Deluxe that used to be available for AppleCare?

- Adrian
Click to expand...
 

Attachments

  • iStat Menu - Temp Sensors & Fans.png
    iStat Menu - Temp Sensors & Fans.png
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  • iStat Menu - CPU Usage.png
    iStat Menu - CPU Usage.png
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Follow-up:
After another SMC reset (I hate working with those loud fans), the problem came back after 30 min, but this time it happened gradually. The CPU Heatsink sensor showed "-" first, and on its own. And only the CPU fan went to 100%. Then after 10-15 min, half of the other sensors went kaput in iStat and all fans went on full drive.

Also, I found my old iMac system disks! The AHT showed no problems on the quick test, and I will run the extended test overnight, as it says it will take a long time.

(If anyone still reads this discussion, I'd love so help!)

- Adrian

Edit: Extended test results (unfortunately, theyre bad)
Code: 
Alert! Apple Hardware Test has detected an error.
4SNS/1/40000000: TCOH- 131.000
What should I do?
 
Last edited:
I don't know what the code means, but you could Google it. No software tool is going to fix your issue, since you have a hardware problem. Tech Tool Pro is a complete waste of money, and Drive Genius is almost a complete waste.

Anyway, the reason your fans are going nuts is specifically because the temperature sensors are going offline. The options are that it's either the SMC going bad or that one (or more) of the temperature sensors are going bad. Yes, despite the fact that multiple sensors are going offline, it's still possible that it's only one. Beyond that, knowing which one is the problem boils down to trial and error. Unfortunately, they intentionally put different connectors on them all so that people can't confuse the system by plugging them into the wrong jack on the logic board, so that also rules out moving them around. Someone is going to have to swap in known-good parts and see what happens.
 
Running Fans May be faulty 1TB Seagate Hard Drive

adriandlm said:
Follow-up:
After another SMC reset (I hate working with those loud fans), the problem came back after 30 min, but this time it happened gradually. The CPU Heatsink sensor showed "-" first, and on its own. And only the CPU fan went to 100%. Then after 10-15 min, half of the other sensors went kaput in iStat and all fans went on full drive.

Also, I found my old iMac system disks! The AHT showed no problems on the quick test, and I will run the extended test overnight, as it says it will take a long time.

(If anyone still reads this discussion, I'd love so help!)

- Adrian

Edit: Extended test results (unfortunately, theyre bad)
Code: 
Alert! Apple Hardware Test has detected an error.
4SNS/1/40000000: TCOH- 131.000
What should I do?
Click to expand...

Faulty Seagate 1 TB hard drives caused this fan problem on some iMacs. Apple is still replacing them. See this article: <http://blog.macsales.com/15165-apple-extends-imac-hard-drive-replacement-program>
and Apple's page: <http://www.apple.com/support/imac-harddrive/>
Hurry, their support could end any time.
 
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