Troubleshooting the MX5, MX10, MX40, and MX80 Fan Tray
Problem Description: The fans in the fan tray are not functioning normally.
Solution Follow these guidelines to troubleshoot the fans:
• Check the alarm LEDs on the front panel.
• Issue the show chassis fan command to get status information about the fans.
user@host> show chassis fan
Item Status RPM Measurement
Fan 1 OK 4560 Spinning at intermediate-speed
Fan 2 OK 4560 Spinning at intermediate-speed
Fan 3 OK 4560 Spinning at intermediate-speed
Fan 4 OK 4560 Spinning at intermediate-speed
Fan 5 OK 4560 Spinning at intermediate-speed
• If the red alarm LED on the front panel lights, issue the show chassis alarms command
to get information about the source of an alarm condition.
If the CLI output lists only one fan failure, and the other fans are functioning normally,
the fan is most likely faulty and you must replace the fan tray.
• Place your hand near the exhaust vents at the side of the chassis to determine whether
the fans are pushing air out of the chassis.
• If a fan tray is removed, a yellow alarm and a red alarm occur.
• The following conditions automatically cause the fans to run at full speed and also
trigger the indicated alarm:
• A fan fails (red alarm).
• The router temperature exceeds the “temperature warm” threshold (yellow alarm).
• The temperature of the router exceeds the maximum “temperature hot” threshold
(red alarm and automatic shutdown of the power supplies).
To view the temperature threshold settings, issue the show chassis
temperature-thresholds command.
user@host> show chassis temperature-thresholds
Fan speed Yellow alarm Red alarm
Item Normal High Normal Bad fan Normal Bad fan
Chassis default 48 54 65 55 75 65
Routing Engine 55 60 75 65 85 70
See Also MX5, MX10, MX40, and MX80 Cooling System Description•
• show chassis fan
129Copyright © 2019, Juniper Networks, Inc.
Chapter 5: Troubleshooting Hardware
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