Technical Documentation

Troubleshooting the T1600 Cooling System

During normal operation, the fans in each fan tray function at less than full speed. The control boards constantly monitor the temperatures detected by sensors on the midplane and router components, adjusting the speed of the fans as necessary. If the router temperature exceeds the acceptable maximum, the control board turns off the power supplies. The following conditions automatically cause the fans to run at full speed and also trigger the indicated alarm:

  • A fan fails (red alarm).
  • One of the fan trays is removed (yellow 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 troubleshoot the fans:

  • If the red alarm LED on the craft interface lights, find the source of the problem by looking at the display on the craft interface. The number of alarm conditions, as well as the source of each alarm, appears on the screen.
  • 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 Troubleshooting Using the T1600 Chassis and Interface Alarm Messages.

  • Place your hand near the exhaust vents at the rear of the chassis to determine whether the fans are pushing air out of the chassis.
  • If the display on the craft interface 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, as described in Replacing the T1600 Fan Tray.

Published: 2009-09-30