Juniper M120 - Maintaining the M120 Fan Trays

should be replaced every 6 months. For procedures to replace the air filter, see
“Replacing an M120 Air Filter” on page 187.
• Spare filter elements should be used within one year of manufacture. Check the date
of manufacture printed on the filter. Store spare filter elements in a dark, cool, and dry
place. Storing the filter elements at higher temperatures, or where they can be exposed
to ultraviolet (UV) radiation, hydrocarbon emissions, or vapors from solvents, can
significantly reduce their life.
CAUTION: Always keep the air filter in place while the router is operating.
Because the fans are very powerful, they could pull small bits of wire or other
materials into the router through the unfiltered air intake. This could damage
the router components.
Related
Documentation
M120 Cooling System Description on page 19•
• Replacing an M120 Air Filter on page 187
• Troubleshooting the M120 Cooling System on page 286
Maintaining the M120 Fan Trays
Purpose For optimum cooling, verify the condition of the fans.
Action Monitor the status of the fans. Each fan tray contains multiple fans that work in unison
to cool the router components. If one fan fails, the host subsystem adjusts the speed
•
of the remaining fans to maintain proper cooling. A red alarm is triggered when a fan
fails, and a yellow alarm is triggered when a fan tray is removed.
• To display the status of the cooling system, issue the show chassis environment
command. The output is similar to the following:
user@host> show chassis environment
Class Item Status Measurement
Temp PEM 0 OK
PEM 1 OK
Routing Engine 0 OK 56 degrees C / 132 degrees F
Routing Engine 1 Absent
CB 0 Intake OK 52 degrees C / 125 degrees F
CB 0 Exhaust A OK 47 degrees C / 116 degrees F
CB 0 Exhaust B OK 44 degrees C / 111 degrees F
CB 1 Intake OK 41 degrees C / 105 degrees F
CB 1 Exhaust A OK 40 degrees C / 104 degrees F
CB 1 Exhaust B OK 42 degrees C / 107 degrees F
FEB 2 Intake OK 44 degrees C / 111 degrees F
FEB 2 Exhaust A OK 44 degrees C / 111 degrees F
FEB 2 Exhaust B OK 48 degrees C / 118 degrees F
FEB 3 Intake OK 46 degrees C / 114 degrees F
FEB 3 Exhaust A OK 46 degrees C / 114 degrees F
FEB 3 Exhaust B OK 52 degrees C / 125 degrees F
Copyright © 2018, Juniper Networks, Inc.264
M120 Multiservice Edge Router Hardware Guide