TroubleshootingHardware Components
turns off the power supplies. The following conditions automatically cause the fans
and impellers to run atfull speed and also trigger the indicated alarm:
A fan or impeller fails (redalarm).
One of the impellers is removed (yellow alarm).
The router temperature exceeds the “temperature warm” threshold (yellow
alarm).
The temperatureof the router exceeds the maximum (“temperaturehot”)
threshold (red alarmand automatic shutdown of the power supplies).
For more information about impeller-related alarms, see “Chassis and
Interface Alarm Messages” on page 209.
To troubleshoot the fans and impellers, follow these guidelines:
If the red alarm LED on the craftinterface lights, check the LCD on the craft
interface forthe source of the problem. The display reports the number of
alarm conditions and the source of each alarm, as describedin “LCD Alarm
Mode” on page 30. For a list of messa ges,see “ Chassis and Interface Alarm
Messages” on page 209.
Issue the following CLI command formore information about the source of
an alarm condition:
user@host> show chassis alarms
If the blue OUTPUT OK LED on an enhanced power supply (or the amber
NO AIRFLOW LED on an original powersupply) is blinking, the airflow passing by
the powersupply might be insufficient. Placeyour hand near the exhaust vents
at the rear of the chassisto determine whether the impellers are expelling air.
If both power supplieshave failed, the system temperature might have
exceeded the threshold, causing the system to shut down. See “All LEDs on
Both Supplies Are Off” on page 215.
If the LCD on the craft interfacereports failure of only one impeller and the
other impellers are functioning norma lly,the impeller i s probably faulty
and needs to be replaced. For replacement instructions,see “Replacing
Hardware Components”on page 139. Forinstructions about returning a faulty
component to Juniper Networks,see “Contacting Customer Support and
Returning Hardware”on page 255.
Troubleshooting Packet Forwarding Engine Components
The following sectionsdescribe how to troubleshoot FPCs and PICs:
TroubleshootingFPCs on page 214
TroubleshootingPICs on page 215
TroubleshootingPacket Forwarding Engine Components 213