Lenovo ThinkCentre A70 7099 Hardware Maintenance Manual page 138

CAUTION:
The heat sink and fan assembly might be very hot. Turn off the computer and
wait three to five minutes to let the computer cool before removing the
computer cover.
To replace the heat sink and fan assembly, do the following:
Figure 51. Removing the heat sink fan duct
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Hardware Maintenance Manual
1. Remove all media from the drives and turn off all attached devices and the
computer. Then, disconnect all power cords from electrical outlets and
disconnect all cables that are connected to the computer.
2. Remove the computer cover. See "Removing the computer cover" on page
122.
3. Remove the front bezel. See "Removing and reinstalling the front bezel" on
page 123.
4. Pivot the drive bay assembly upward, remove the four screws that secure the
heat sink fan duct, and then lift the heat sink fan duct up to remove it from
the chassis.
5. Disconnect the heat sink and fan assembly cable from the microprocessor fan
connector on the system board. See "Locating parts on the system board" on
page 120.