Juniper MX2010 Hardware Manual page 721

Solution
To troubleshoot the cooling system:
1. Place your hand near the exhaust vents at the back of the chassis to determine whether the fans are
pushing air out of the chassis.
2. If the red alarm LED on the craft interface lights, look at the craft interface display to find the source
of the problem. The number of alarm conditions, as well as the source of each alarm, appears on the
screen.
3. If the craft interface display lists only one fan failure and the other fans are functioning normally, the
fan is probably faulty and you need to replace the fan tray.
4. Use the CLI to check the status of the fans. For example, you can issue the following command to get
information about the source of an alarm condition:
user@host>show chassis alarms
For information about the alarms (see
Table 101: MX2010 Cooling System Alarms
Component
Fans
Table 101 on page
Alarm
Type CLI Message
Red fan-name Failure
707).
Alarm Condition
A fan has failed.
Solution
Replace the fan tray.
707