Cisco GSR12/60 - 12012 Router -AnyLAN, SONET/SDH Installation And Configuration Manual page 228

Troubleshooting the Cooling Subsystem
Both blower modules are needed to provide sufficient cooling air through the system. Each
blower module contains three variable speed fans and a controller card. There are two LEDs
on the blower module faceplate visible through the blower module front cover.
The green LED, when lit, indicates that the blower module is functioning. Check the
following to help isolate a problem with the cooling system:
•
When you start up the system, do the blower modules go on?
Note
normal operation the green fans OK LED should be on. Listen for the blower fans. In noisy
environments, place your hand at the back of the frame, behind the blower modules, both
top and bottom, to feel for air being forced out the exhaust vents.
— If the blower modules come on, the –48 VDC line from the power supply to the
— If one or both of the blower modules do not come on, there could a problem with
— If one or both of the blower modules do not come on and the power supply output
— If the blower module does not come on, there could be a problem with the blower
5-16 Cisco 12012 Gigabit Switch Router Installation and Configuration Guide
To determine if a blower module is operating, visually check the two LEDs. Under
blower is good.
either the blower module or the –48 VDC power. If both blower modules do not
come on, it is likely there is problem with the –48 VDC output from the power
supply. Check the red output fail LED on each power supply. If the output fail LED
on a power supply is on, the power supply is faulty and should be replaced.
fail LED is off (–48 VDC is OK), ensure that the blower module is seated properly
in the frame. Remove the blower module snap-on front cover, loosen the two
captive screws on the blower module faceplate, grasp the blower module handle and
pull the blower module out and then firmly push to reseat the blower module in the
frame. Reinstall the blower module front cover.
module controller card. The controller card controls the speed of each fan. Fan
speed is dependent on the air temperature detected on the cards in the upper and
lower card cages and the power supplies in the power supply bay. Changes in air
temperature in one of those locations changes the fan speed which forces less or
more cooling air through both card cages and the power supply bay.