Introduction
Keep your CPU running cool by replacing the CPU Fan.
Tools
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Lay your iMac front side down on a table with the lower edge facing yourself.
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Loosen the single Phillips screw in the center of the access door.
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Remove the access door from your iMac.
 
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Remove the following 12 screws securing the front bezel to the rear case:
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Eight 13 mm T8 Torx.
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Four 25 mm T8 Torx.
 
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Gently lift the front bezel from its top edge off the rear case.
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Once the top edge of the front bezel has cleared the rear case, rotate the front bezel toward the stand and lift it off the rear case.
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Rotate the front bezel away from the rest of the device and lay it above the top edge of the iMac.
 
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Pull the LCD temperature sensor connector straight up off its socket on the logic board.
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(located at the top of the logic board on the 24")
 
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Remove the two T6 Torx screws securing the display data cable to the logic board.
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Use the attached black tab to pull the display data cable connector straight away from the logic board.
 
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Remove the eight T8 Torx screws securing the display panel to the rear case.
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Lift the display panel from its left edge and rotate it toward the right edge of the iMac.
 
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With the display panel still lifted, disconnect the four inverter cables.
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(combined into one plug in on the 24")
 
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Disconnect the left speaker cable connector from the audio board by pulling it straight away from its socket.
 
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Disconnect the CPU fan connector from the logic board by pulling it straight up from its socket.
 
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To reassemble your device, follow these instructions in reverse order.
The grid won't fall off by itself. You'll have to help it. Use the smallest screwdriver you have; the Torx 6 worked fine for me. It should enter in one of the many holes composing the grid. Use it as a lever to ploy the grid a little bit. You may catch it with your fingers and that's it.
Be carefull not to damage the hole by a too strong leverage.
Laurent -
much more safer to use duct tape, instead of torx 6. (glue it along the length of the grid and pull). it will loose instantly and smooth;)
Hofmann78rus -
Anyone know a guide to replace the plastic piece this screw connects to? I accidentally forgot this step - went to remove the front bezel and bent the plastic piece the access door connects to.
Jason Augustin -