Apple iMac (17-inch Mid 2006) - Manual (Page 97)

iMac (17-inch Mid 2006/Late 2006 CD) Take Apart —Hard Drive Fan 
Remove the Hard Drive Fan
Carefully pull the hard drive fan cable from under the chassis.
Lift the hard drive fan straight up and off three mounting posts.
Replacing the Hard Drive Fan
Route the hard drive fan cable under the metal chassis and above the I/O ports.
Align and install the hard drive fan on mounting posts. Push it down snug onto the posts.
Replace the logic board.
Replace the optical drive.
Replace the hard drive.
Replace the speakers.
Replace the display panel.
Replace the lower EMI shield.
Replace the front bezel.
Replace the memory.
Replace the memory access door.
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