Nortel North American DMS-100 Instruction Manual page 94

Repairing and replacing NT3X90AF cooling units
15 Install the eight screws that secure the mounting flanges on the sides of the
cooling unit to the frame. To install the screws, use a 5/16-inch ratchet and
extension.
16 Reinstall the side rail covers on the front of the frame.
At the back of the cooling unit
17 Reconnect the lugs that connect the frame wiring to the cooling unit.
At the front of the cooling unit
18 Replace the air intake grill and filter at the front of the unit.
At the FSP
19 Turn OFF the FAN FAIL OVERRIDE switch.
20 Go to step 43.
At the front of the cooling unit
21 Remove the screws that secure the side rail covers to the frame.
22 Remove the eight screws that secure the mounting flanges on the sides of the
cooling unit to the frame. To remove the screws, use a 5/16-inch ratchet and
extension.
23
Ease the cooling unit toward you until the unit is half way out of the frame.
24 Inspect the fans in the cooling unit and determine how many fans work.
If
all fans work correctly but the
FAN FAIL lamp remains on
one or more fans do not work
Note: The failure of one or more fans to work can indicate a wiring
harness that has faults or loose connections or that the fan(s) require(s)
replacement.
25 Remove the fuses from the front of the cooling unit.
26 Inspect the wiring harness of the cooling unit for damaged and/or a loose
connection at the fans or terminal blocks.
DMS-100 Family Trouble Locating and Clearing Procedures Volume 2 of 2 LET0015 and up
Trouble locating and clearing procedures
WARNING
Loss of frame cooling
Removal of the cooling unit for an extended period
of time can cause the equipment in the frame to
overheat.
Do
step 43
step 25
-7
(continued)