Troubleshooting the MX960 Cooling System

Problem

The fans in a fan tray are not functioning normally.

Solution

• Check the fan LEDs and alarm LEDs on the craft interface.
• If the red alarm LED on the craft interface lights, use the CLI to get information about the source of an alarm condition: user@host> show chassis alarms.

  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).