• Supported Platforms
• T640 Routers

• Related Topics
• T640 Cooling System Description
• Maintaining the T640 Air Filters
• Maintaining the T640 Fan Trays
• Replacing the T640 Cooling System Components

Troubleshooting the T640 Cooling System

Problem

The following alarms and LEDs indicate a problem when:

• A fan fails (red alarm).
• One of the fan trays is removed (yellow alarm).
• A front or rear fan trays is functioning at 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.
• 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).

Note: If the router temperature exceeds the acceptable maximum, the T-CB turns off the power supplies.

During normal operation, the fans in both front and rear fan trays function at less than full speed.

Solution

To troubleshoot the fans, follow these guidelines:

• 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 T640 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 a T640 Fan Tray.