Nortel Passport 15000 Hardware Installation And Maintenance page 447

• When the fan was removed to gain access to a fan controller module or a
temperature sensor, insert the same fan.
Procedure steps
1 Put tape on the fan blades to temporarily prevent them from spinning
freely when the airflow from the other fans reaches the replacement as it
is being installed. When power is applied to fan blades that are freely
spinning in the opposite direction from operation, the reversal under
power strains the fan motor.
2 Orient the fan with the vacant cavity on the cooling unit so that you:
• aim the nose of the fan blades towards yourself
• position the power cable (indicated in the figures) relatively the same
as the others
• align the 2 holes of the shroud with the 2 holes on the face of the
cooling unit
• can read the words on the central hub of the fan shroud
3 Gently and evenly slide the fan assembly straight into the opening. Stop
when the rear of the shroud touches the front face of the cooling unit.
4 Loosely fasten an M4 screw through the fan shroud into the face of the
cooling unit.
5 Insert one notch of the finger guard grill under the M4 screw head so that
the caution label on the grill:
• is horizontal
• faces where it can be read
6 Align the second grill notch with the other hole in the fan shroud and
thread the remaining M4 screw through the notch and shroud into the
cooling unit.
Ensure that the rungs of the grill notches are centered under the screw
heads for maximum grip.
7 Tighten the screws to snug plus a 1/5 turn. Snug means the screw head,
grill rung, and shroud are all touching. If you over tighten the screws, you
risk having to replace the entire cooling unit. If you under tighten the
screws, vibrations from the fans can free the grill and then risk having a
loose fan fail prematurely.
Passport 15000, 20000 Hardware Installation, Maintenance, and Upgrade
Chapter 17 Hardware procedures 447
5.2S2