iMac about to take off?

[Matski]

I have a iMac early 2009 20" 2.66 which sounds like its going to take off. There is a loud whirling/spinning sound which is constant as soon as I turn it on, which i think is the fan, as air is constantly blowing out the back.

Any idea's why the fan is doing this or might it be something else?

 

[simsaladimbamba]

Have you tried an SMC reset yet?

Intel-based Macs: Resetting the System Management Controller (SMC) (Apple Support Site)

 

[Matski]

Have you tried an SMC reset yet?

Intel-based Macs: Resetting the System Management Controller (SMC) (Apple Support Site)

Not yet. How do I do this?

 

[simsaladimbamba]

Not yet. How do I do this?

Follow the link I provided and it will explain it to you.

Or just look at this copy and paste job:

Resetting the SMC for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve

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.

In short, it will reset your fan speeds to standard, unless there is a process that hogs the CPU that much and your room being a bit too warm.

 

[Matski]

Follow the link I provided and it will explain it to you.

Or just look at this copy and paste job:



In short, it will reset your fan speeds to standard, unless there is a process that hogs the CPU that much and your room being a bit too warm.

Thanks. I've reset the SMC, that did nothing. I then reset the PRAM and that did nothing. Room is fairly cool, so its not overheating. I also looked at the CPU and that is running normally, as I'm not running anything other than Safari.

Still unsure why the fan is so loud and runs constantly?

 

[Rodster]

Thanks. I've reset the SMC, that did nothing. I then reset the PRAM and that did nothing. Room is fairly cool, so its not overheating. I also looked at the CPU and that is running normally, as I'm not running anything other than Safari.

Still unsure why the fan is so loud and runs constantly?

It's possible the thermal paste is doing it's job and/or the iMac has accumulated dust bunnies. I don't own an iMac just from past PC/electronics experience.

 

[Matski]

It's possible the thermal paste is doing it's job and/or the iMac has accumulated dust bunnies. I don't own an iMac just from past PC/electronics experience.

So, I need to spray some air through it, to clear any dust? I did notice a little dust when I installed a new HDD.

 

[chasemac]

You might try unplugging all peripherals besides keyboard, mouse and restart to see what happens. Not sure if you have anything else plugged into your iMac which may be the cause.

 

[ctucci]

Thanks. I've reset the SMC, that did nothing. I then reset the PRAM and that did nothing. Room is fairly cool, so its not overheating. I also looked at the CPU and that is running normally, as I'm not running anything other than Safari.

Still unsure why the fan is so loud and runs constantly?

Could it be accumulated dust on the bottom and the on the fan port on the back?

Could also be dust on the fans/heat sinks, given that it's an 09. That's a fair amount of time for fans and heat sinks to collect dust. If someone in the house smokes, that accelerates the problem.

If you're willing, ifixit has a guide you can use to take a look internally: https://www.ifixit.com/Guide/iMac+Intel+20-Inch+EMC+2266+Heat+Sink+Replacement/935

Not to replace the heat sink, just to have a look and perhaps clean debris.

 

[53kyle]

Is it possible that when you were replacing your hard drive, that you might have accidentally unplugged/severed a wire for one of the thermal sensors? Sometimes if that happens, the fans will automatically run on highest just in case it starts getting hot and won't get detected.

 

[Rodster]

So, I need to spray some air through it, to clear any dust? I did notice a little dust when I installed a new HDD.

That wouldn't hurt although it might be better to first try and vacuum the visible dust from the vents before blasting it with air. If you decide to use air, make sure you do it in short burst.

Also, I meant to say the thermal paste might not be doing it's job. Sorry for the typo.

 

[Matski]

Is it possible that when you were replacing your hard drive, that you might have accidentally unplugged/severed a wire for one of the thermal sensors? Sometimes if that happens, the fans will automatically run on highest just in case it starts getting hot and won't get detected.

No. I carefully installed the hdd. The fan was a problem before I installed the hdd, so I'm thinking dust could be the problem.

 

[khedden]

No. I carefully installed the hdd. The fan was a problem before I installed the hdd, so I'm thinking dust could be the problem.

How much of a problem was it? The same kind of problem -- jet plane take-off levels?

I just mention this because there's a thermal sensor for the hard drive which I believe you have to reverse on a third party HDD install. Check the iFixit guide to see what I'm talking about.

If you already did all that when installing, then ignore me.

 

[Matski]

How much of a problem was it? The same kind of problem -- jet plane take-off levels?

I just mention this because there's a thermal sensor for the hard drive which I believe you have to reverse on a third party HDD install. Check the iFixit guide to see what I'm talking about.

If you already did all that when installing, then ignore me.

Reverse the thermal sensor? You mean don't have it flat side down?

I just found this link. Nothing about reverse the sensor...

https://www.ifixit.com/Guide/iMac+Intel+20-Inch+EMC+2266+Hard+Drive+Replacement/919

 

[khedden]

Reverse the thermal sensor? You mean don't have it flat side down?

I just found this link. Nothing about reverse the sensor...

https://www.ifixit.com/Guide/iMac+Intel+20-Inch+EMC+2266+Hard+Drive+Replacement/919

I was talking about this: https://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2308+Hard+Drive+Replacement/1766

Step 10.

But that's the late 2009 model. I didn't know which you have.