Troubleshooting the M10i Fan Tray

Problem

The fans in the fan tray are not functioning normally.

Solution

To troubleshoot the cooling system:

1. Check the alarm LEDs on the HCM:
   • If the yellow or red alarm LED on the HCM is lit, issue the show chassis alarms CLI command to view a more detailed description of the alarm cause:
     
     

     user@host> show chassis alarms

     For a list of messages that can appear in the output, see Table 1.

   • If all the LEDs on the HCM are not lit, it might indicate that power is not being provided to the router. See Troubleshooting the M10i Power System. In some cases, the Routing Engine shuts down the router by turning off the power supplies if the temperature passes the acceptable maximum.
2. Check the status of the cooling system by issuing the show chassis environment command. The output includes an entry for each fan and temperature for components, as shown in this example:
   
   

   user@host> show chassis environment

   Class Item                           Status     Measurement
   Power Power Supply 0                 OK
         Power Supply 1                 OK
         Power Supply 2                 Absent
         Power Supply 3                 Absent
   Temp  Intake                         OK         25 degrees C / 77 degrees F
         FPC 0                          OK         30 degrees C / 86 degrees F
         FPC 1                          OK         28 degrees C / 82 degrees F
         Lower Power Supplies           OK         28 degrees C / 82 degrees F
         Upper Power Supplies           OK         28 degrees C / 82 degrees F
         Upper Power Supplies           OK         28 degrees C / 82 degrees F
         CFEB Intake                    OK         27 degrees C / 80 degrees F
         CFEB Exhaust                   OK         35 degrees C / 95 degrees F
         Routing Engine 0               OK         32 degrees C / 89 degrees F
         Routing Engine 1               Absent
   Fans  Fan Tray 0                     Absent
         Fan Tray 1 Fan 1               OK         Spinning at normal speed
         Fan Tray 1 Fan 2               OK         Spinning at normal speed
         Fan Tray 1 Fan 3               OK         Spinning at normal speed
         Fan Tray 1 Fan 4               OK         Spinning at normal speed
         Fan Tray 1 Fan 5               OK         Spinning at normal speed
         Fan Tray 1 Fan 6               OK         Spinning at normal speed
         Fan Tray 1 Fan 7               OK         Spinning at normal speed
         Fan Tray 1 Fan 8               OK         Spinning at normal speed

   For further description of the output from the command, see the Junos OS System Basics and Services Command Reference.

3. If you receive a temperature alarm:
   • Check the temperature of each component by issuing the show chassis environment command. Temperature sensors on the components detect temperatures above the acceptable range. Verify that the temperature is OK for each component.
   • Check the room temperature.
   • Check the airflow and clearance around the chassis. For the fan tray to function properly, the clearance around the chassis must be sufficient for unobstructed airflow. See Clearance Requirements for Airflow and Hardware Maintenance. For a graphic depiction of the airflow, see M10i Fan Tray Description.
   • Check if a faulty fan is causing the temperature to be elevated for one or more components.
4. Check the fan tray:
   • Check the status of the fans by issuing the show chassis environment command. Verify that the status is OK and that the fans are Spinning at Normal Speed.
   • If the fan tray fails, determine whether you can distinguish individual blades in a fan—this is not possible when the fans are rotating at normal speed.
5. If you are unable to correct the problem, replace the fan tray with a spare. For instructions, see Replacing an M10i Fan Tray. If the LED lights correctly on the spare, the original fan tray is faulty. Return it to Juniper Networks for replacement, as described in Returning a Hardware Component to Juniper Networks, Inc..