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Cisco ASR 9000 Series Aggregation Services Router Overview and Reference Guide
OL-17501-09
Chapter 2 Functional Description
Cooling System Functional Description
Figure 2-79 shows how to replace the foam media inside one of the two side air filters.
Figure 2-79 Cisco ASR 9922 Router Chassis Side Air Filter
Speed Control
The cooling system adjusts its speed to compensate for changes in system or external ambient
temperatures. To reduce operating noise, the fans have variable speeds. Speed can also vary depending
on system configurations that affect total power dissipation. If lower power cards are installed, the
system could run at slower speeds; if higher power cards are installed, the system could run at faster
speeds
Fan speed is managed by the RSP/RP card and the controller card in the fan tray. The RSP/RP monitors
card temperatures and sends a fan speed to the controller card.
If the failure of a single fan within a module is detected, the failure causes an alarm and all the other fans
in the fan tray go to full speed.
Complete failure of one fan tray causes the remaining fan tray to operate its fans at full speed
continuously until a replacement fan tray is installed.
1Loosen thumb screws. 3Remove foam filter media.
2Rotate and lower inner frame.
1Loosen thumb screws 3Remove foam filter media
2Rotate and lower inner frame
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