Nortel North American DMS-100 Instruction Manual page 72

1-56 Trouble locating and clearing procedures (continued)
Repairing and replacing NT3X90AA cooling units
13
297-8021-544 Standard 14.02 May 2001
If
fans work correctly but FAN
FAIL lamp remains on
one fan does not work
other than listed above
Note 1: A fan that does not work indicates a wiring harness, loose
connections, or a fan that requires replacement.
Note 2: The operation of all fans with a lit FAN FAIL lamp indicates a air
flow sensor that has faults.
Inspect the wiring harness for the cooling unit. Look for damage and/or a
loose connection at the fans or terminal blocks.
(continued)
Air flow sensor switch
Fan
Do
step 33
step 13
step 85