• Green—Fan tray is functioning properly.
• Red—There is a fault detected in the fan tray.
If the air temperature inside the chassis rises, blower speed increases to provide additional cooling air to the
internal components. If the internal air temperature continues to rise beyond the specified threshold, the system
environmental monitor shuts down all internal power to prevent equipment damage because of excessive heat.
If the system detects that one or more of the fans in the fan tray has failed, it displays a warning message on
the system console. Except for the Cisco ASR 9922, the remaining fans go to full speed to compensate for
the loss of the failed fan.
The Cisco ASR 9922 supports dynamic fan-speed algorithm (DFSA). DFSA sets the fan speed based on the
temperature change. In case of a fan failure on the Cisco ASR 9922, the software increases the fan speed to
the next level.
Note
Due to air leakage, the chassis should not be operated with any of the fan trays completely missing. Replace
any missing fan tray within five minutes. Any fan tray replacement should be performed when the chassis is
back to room temperature.
Caution
Power Module Fans
Each AC or DC power module is equipped with two fans that draw cooling air in through the front of the
power module and force warm air out the back of the power tray:
• If the power source is within the required range, the power supply fan remains on.
• If a fan fails:
• Power module detects an internal overtemperature condition.
• Fault and Temp indicators light.
• Power module sends an overtemperature warning to the system and then shuts down the system.
For additional power supply troubleshooting information, see Troubleshooting the Power Subsystem, on page
203.
For the RSP/RP to communicate properly to a power module in a power tray, input power to at least one of
the three power modules in the power tray should be present.
Note
Overtemperature Conditions
The following console error message indicates that the system has detected an overtemperature condition or
out-of-tolerance power value inside the system:
Queued messages:
Cisco ASR 9000 Series Aggregation Services Router Hardware Installation Guide
218
Troubleshooting the Installation
Power Module Fans
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