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Fan is always on
- Thread starter 420benz
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There are three fans in a 2011 iMac. If you’ve never noticed them before then you must never have stressed the computer much at all (although all three fans are always running at at least their minimum speed), have bad hearing, or a loud room. If a fan runs at full blast from when you turn your computer on then something inside has failed, often a temperature sensor. You should be able to run Apple Hardware Test by holding down the D key as you boot up the computer. This may give you an error code that you can then Google to find out more.
Yes, most probably one sensor is dead. You can use a tool like Mac Fan control to figure out which one is failing. Just manually reduce the speed one by one slowly until you find which one is causing the noise.
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It happened to me yesterday while servicing my old iMac, I broke the hd temperature sensor connector and now the central fan is always full speed. Not sure in your model, but in a 24inch the central fan is the one connected to the back ventilation hole. Maybe you can also spot it putting the hand in the back.
If it is the HD one, I think that should be safe for you to just use the same app to control the temperature. For other sensors like GPU and CPU, it will be more risky.
If you want to fix it for good, you will need to open the Mac and do the service yourself, depending on the sensor it will be more or less difficult. HD/SuperDrive are the easier ones and you can find replacements for less than 10$. CPU and specially GPU one will require you to basically remove your logic board.
Macs Fan Control Download for macOS & Windows (Boot Camp)
It happened to me yesterday while servicing my old iMac, I broke the hd temperature sensor connector and now the central fan is always full speed. Not sure in your model, but in a 24inch the central fan is the one connected to the back ventilation hole. Maybe you can also spot it putting the hand in the back.
If it is the HD one, I think that should be safe for you to just use the same app to control the temperature. For other sensors like GPU and CPU, it will be more risky.
If you want to fix it for good, you will need to open the Mac and do the service yourself, depending on the sensor it will be more or less difficult. HD/SuperDrive are the easier ones and you can find replacements for less than 10$. CPU and specially GPU one will require you to basically remove your logic board.