Cooling System Components

The cooling system has the following components. All are hot-removable and hot-insertable, as described in Field-Replaceable Units (FRUs).

• Air intake vent, air filter, and intake cover—Provide an opening for room air to enter the router. They are located at the bottom of the chassis front, below the cable management system, as shown in Figure 1. The air filter is removable and covers the air intake vent, preventing dust and other particles from entering the cooling system. For maintenance and replacement instructions, see Maintaining the Air Filter. The nonremovable air intake cover is located behind the air filter and provides EMC shielding.

  Do not remove the air filter for more than a few minutes while the router is operating. The fans and impellers are powerful enough to draw in foreign material, such as bits of wire, through the unfiltered air intake, which could damage router components.

• Front cooling subsystem—Cools the FPCs, PICs, and midplane. It includes a fan tray located behind the cable management system and a large, central impeller behind the craft interface. For replacement instructions, see Replacing the Fan Tray and Replacing the Front Impeller Assembly.
• Rear cooling subsystem—Cools the SFMs, host module, PCGs, and power supplies. It includes one impeller located at the upper right of the chassis rear and another at the lower left, as shown in Figure 2. The upper and lower impellers are not interchangeable. For replacement instructions, see Replacing the Rear Lower Impeller Assembly and Replacing the Rear Upper Impeller Assembly.