Technical Documentation

Troubleshooting the T640 Cooling System

During normal operation, the fans in each fan tray function at less than full speed.

The following alarms, LEDs, and other conditions indicate a problem with the cooling system:

A red alarm indicates that temperature of the router exceeds the maximum (“temperature hot”) threshold.
Automatic shutdown of the power supplies was caused by the temperature of the router exceeding the maximum (“temperature hot”) threshold. The control board turns off the power supplies because the router temperature exceeds the acceptable maximum.
A red alarm indicates that a fan failed.
A yellow alarm indicates that the router temperature exceeds the “temperature warm” threshold.
A yellow alarm indicates that one of the fan trays was removed.
One or more fans in a fan tray function 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.

To troubleshoot the cooling system:

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 red alarm LED on the craft interface lights, look at the craft interface display to find the source of the problem. The number of alarm conditions, as well as the source of each alarm, appears on the screen.
If the craft interface display 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.
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 Table 1..

Table 1: T640 Cooling System Alarm Messages

Component	Alarm Type	LCD Display Message	CLI Message	Alarm Condition	Solution
Fans	Red	Fan Failure	fan-name Failure	A fan has failed.	Replace the fan tray.
	Red	Fans Missing	Too many fans missing or failing	A fan tray is missing or too many fan trays have failed.	Reinstall the fan tray in the chassis.
	Yellow	Fan Removed	fan-name Removed	A fan tray has been removed.	Reinstall the fan tray in the chassis.
	Yellow	Mix of FAN-TRAYS	Minor – Mix of FAN-TRAYS	A mix of standard front fan trays and quiet front fan trays are installed in the chassis. Note: During normal operations, mixing the standard and quiet fan trays is not supported.	Check that all fan trays are either standard fan trays or quiet fan trays. Install the correct fan trays. Note: During an upgrade, ignore this alarm.
Temperature sensors	Red	Temperature Hot	Temperature Hot	The chassis temperature exceeded the hot temperature threshold. If this condition persists, the router shuts down.	Verify that the room temperature is within acceptable limits. Verify that there is sufficient air flow. Verify that the cooling system in the chassis is operating properly.
	Red	Sensor Failure	Temperature sensor failure	A temperature sensor failed.	Contact JTAC.
	Yellow	Temperature Warm	Temperature Warm	The chassis temperature exceeded the warm temperature threshold.	Verify that the room temperature is within acceptable limits. Verify that there is sufficient air flow. Verify that the cooling system in the chassis is operating properly.