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Model A1311 / Mid 2010 / 3.06 & 3.2 GHz Core i3 or 3.6 GHz Core i5 Processor

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How do I know if I need to replace temperature sensors

The fan on my iMac is frequently running at high speed, often shortly after start up and not under heavy use.

I have installed and run TGPro app which has identified possible problem with temperature sensors "optical drive, LCD, unknown name".

Is there any way of checking these or is it easier to replace?

Grateful for any other advice.

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Can you post a screen snap of the main TG Pro window so we can see what you see.


Did you change to hard drive?


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If your iMac is running hot or running for extended periods of time I would first check to see if it is full of dust. If you are going that deep into the iMac and you have a compressor I would remove the glass, remove the aluminum front panel and then the LCD panel and take the compressor and blow out all the dust in the interior of the Mac with special attention to the fan(s) which will likely be caked in dust.

If your iMac looks very clean inside then I would consider the temperature sensor however in pretty much any older Mac and every computer I service I have almost always discovered that it is quite full of dust.

If you don't feel comfortable pulling the LCD you can try blowing dust out by shooting compressed air through the slot up top. I would not recommend using canned air, mainly because it is not powerful enough and second because you will wind up burning through a can trying to fix the problem and likely won't have enough pressure. Also not sure how much more environmentally friendly the new formulations are vs the ozone killing older stuff.

If you can't find a compressor handy, look for a shop, garage or auto body painter but try and find one that has a moisture trap on their system. Or just go to a place like Princess Auto or Harbour Freight and pick up a light duty one. They are also handy for pumping up car tires.

One word of caution when using a compressor, use it gently on the fan blades, too much force on older brittle blades can cause them to disintegrate.

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You can also buy a can of can'ed air to blow out the dust Staples Electronics Duster 3.5oz, Single. I would also use a soft paint brush to loosen the dust.


Problem with canned air on a job like this is that you need to shoot a lot of it into the Mac and the more you use it the colder and weaker it gets so it's not that useful. Unless you pull the screen and can get at the insides shooting this stuff down the vent holes probably won't do anything.

Dusting off negs canned air is great because it's a short blast but longer squirts not so much.

Oh and the other problem is if you tip the can the wrong way you wind up shooting the liquid onto whatever it is you are working on.


I don't know about you but I don't have any issues! Maybe you are using it with to long a blast and not first loosening the dust with a soft brush. I use a standard can which lasts be quite a few days and I do get some really dirty systems in which I need to clean before I can even try fixing them.


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Jon Lawler will be eternally grateful.
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