Troubleshooting the Cooling Subsystem
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
5-18
•Power supply fan tray—This fan tray is mounted in the lower right corner of the router
enclosure.
Each fan tray operates from +24 VDC that is distributed to it through the backplane from a
DC-DC converter on the CSC. A recessed, blind-mating connector in the back of each fan
tray provides connectivity to the backplane.
Both fan trays are essential; they provide sufficient cooling air for the router’s components
and electronic circuitry. The card cage fan tray incorporates six variable-speed fans; the
power supply fan tray incorporates four variable-speed fans.
To isolate a problem with the router’s cooling subsystem, make the following assessments:
•When the system is started up, do the fan trays begin to come up to normal rotational
after about two seconds?
Note To determine if the fan trays are operating, first listen for the hum of the fans. In a
noisy environment, you might have to place your hand at the top rear of the r outer enclosure
to feel the air being exhausted from the fan tray vents.
—If both fan trays operate as expected, the +24 VDC power from the DC-DC
converter on the CSC is confirmed as present and operational.
—If one fan tray or the other does not operate as expected, there could be a problem
with the voltage being supplied to the fan tray. In this case, check the status of the
power supply LEDs on the CSC faceplate (see Figure1-14).
If the left fan tray LED on the CSC faceplate is on (amber), reseat the card cage fan
tray in the backplane, as follows:
1Remove the air filter assembly from the chassis.
2Loosen the two captive installation screws securing the fan tray to the chassis
frame.
3Grasp the fan tray carrier by its extraction/insertion ring and pull the unit part
way out of the slot.
4Firmly reseat the fan tray in the slot.