Nortel North American DMS-100 Instruction Manual page 74

1-58 Trouble locating and clearing procedures (continued)
Repairing and replacing NT3X90AA cooling units
At the back of the cooling unit
18
At the cooling unit
19
20
21
22
23
24
25
26
27
28
29
30
At the back of the frame
31
32
33
34
297-8021-544 Standard 14.02 May 2001
Unplug the connector at the back of the unit.
Disconnect the wiring to the airflow sensor switch from the fan. Note the
position and color of the wires.
Note the position of the air flow switch on the fan.
Remove the sensor switch from the switch bracket. Lay the switch to one
side.
Cut the two tie wraps that secure the power cord to the fan.
Remove the four screws, spacers, nuts, and washers that secure the fan to
the cooling unit.
Disconnect the power cord at the fan terminals.
Remove the fan.
Plug a new fan into the power cord.
Mount the new fan. Ensure that you install the fan to allow air to flow toward
the top, as indicated on the label. Secure with screws, spacers, nuts and
washers.
Secure the power cord to the fan with new tie wraps.
Reinstall the wiring to the sensor switch, as noted in step 19.
Reinstall the sensor switch to the switch bracket. Secure the sensor in
position with screws, nuts, and washers.
Reconnect the connector at the back of the cooling unit.
Inspect the fan operation.
If the fan
works correctly, but did not
work in step 12
did not work correctly, and did
not work in step 12
Inspect the sails of the air flow sensors. Replace or repair any sails that
appear to have faults.
Disconnect the wiring to one of the sensor switches. Note the position and
color of the wires.
If the FAN FAIL lamp
remained on when you discon-
nected the wiring to the air flow
sensor
(continued)
Do
step 62
step 85
Do
step 37