# show fans

IMPORTANT:

On some platforms, the output will change to show the state of the fan controller and the speed of each fan.
Table 1. show fans Command Output Descriptions

Field | Description
--- | ---
Upper Fan Controller | The Upper Fan Tray pulls air through the chassis and exhausts it from the upper rear of the chassis.
Lower Fan Controller | The Lower Fan Tray pulls ambient air into the chassis and pushes it upward and through the chassis.
State | Displays the operational state of the fan tray and fan tray controller. The possible states are:
Normal: There are no errors. This is the normal operating condition.
Multiple Fan Failure: Multiple fans on the fan tray have failed.
Single Fan Failure: A single fan on the fan tray has failed.
Heartbeat Error: The redundant fan controller on the fan tray did not respond to the heartbeat signal.
Fan A Communication Error: An error has occurred on the primary fan controller bus for the fan tray.
Fan B Communication Error: An error has occurred on the redundant fan controller bus for the fan tray.
Communication Error: An inter-bus communication error was experienced between the primary and redundant fan controllers on the fan tray.
NOTE: If any of the error conditions above are reported for your system, it is likely that the fan tray will need to be repaired or replaced. Please contact your local sales representative for additional information.
Speed | Indicates the rate at which the fans on the fan tray are spinning as a percentage of the maximum speed. Lower percentages indicate that the fans are having to do less work to keep the chassis cool and should be the normal operating condition. Higher percentages indicate that the fans are having to work harder to keep the chassis cool. This could be due to a number of reasons including improper ventilation of the chassis, individual fan failures, or even a dirty air filter. Please refer to the System Administration Guide for information on troubleshooting the problem. NOTE: Systems equipped with the dual-speed fan tray controller display the fan speed as follows: Normal: The fans on the fan tray are operating at a normal speed to maintain a safe operating temperature for the chassis and its components. High: The fans on the fan tray are operating in high speed to maintain a safe operating temperature for the chassis and its components.
Temp | Displays the temperature of the chassis in degrees Celsius at the fan tray. The ambient air temperature shown for the Lower Fan Controller should not exceed 40 degrees Celsius for an extended period of time. The exhaust air temperature shown for the Upper Fan Controller should not exceed 55 degrees Celsius. For additional information on air temperature, refer to the description of the show temperature command in this guide.