Troubleshooting the M7i Fan Tray

Problem

The fans in the fan tray are not functioning normally.

Solution

The router's single fan tray provides cooling for the router, including the CFEB or CFEB-E, PICs, power supplies, and Routing Engine.

The cooling system draws in room air through the air intake vent on the left side of the chassis. After entering the chassis, the air stream separates into separate flows for the front and rear components. For a graphic depiction of the airflow, see M7i Cooling System Overview.

For the cooling system to function properly, the clearance around the chassis must be sufficient for unobstructed airflow. See M7i Router Clearance Requirements for Airflow and Hardware Maintenance.

During normal operation, the fans in the fan tray function at less than full speed. The router constantly monitors the temperatures detected by sensors on the router components, adjusting the speed of the fans as necessary. If the router temperature exceeds the acceptable maximum, the router turns off the power supplies.

The following conditions automatically cause the fans to run at full speed and 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).

For more information about cooling-related alarms, see Overview of Troubleshooting Resources for the M7i Router.

To troubleshoot the fans:

• If the red alarm LED on the craft interface lights, use the show chassis alarms command to determine the source of the problem. The display reports the number of alarm conditions and the source of each alarm. For a list of messages, see Overview of Troubleshooting Resources for the M7i Router.
• Issue the show chassis alarms command for more information about the source of an alarm condition.
• If both power supplies have failed, the system temperature might have exceeded the threshold, causing the system to shut down. See Troubleshooting the M7i Power System When the LEDs on All M7i Power Supplies Are Blinking or Off.
• If the fan tray has failed, it must be replaced for the router to operate normally. For replacement instructions, see Replacing the M7i Fan Tray. For instructions about returning a faulty component to Juniper Networks, see Contacting Customer Support.