Troubleshooting The Cooling System; Figure 35: Airflow Through The Chassis - Juniper MX240 Hardware Manual

MX240 Ethernet Services Router Hardware Guide

Troubleshooting the Cooling System

The router cooling system is a fan tray and an air filter, both of which are located
vertically in the rear of the chassis (see Figure 1 on page 6). Figure 35 on page 82
shows the airflow through the router. To function properly, the entire cooling system
requires an unobstructed airflow and proper clearance around the site, as described
in "Preparing the Site for Router Installation" on page 29.

Figure 35: Airflow Through the Chassis

To verify that the cooling system is functioning normally:
82
Troubleshooting the Cooling System
RE might still be booting or the SCB is not receiving power. For more information,
see "SCB Components" on page 13.
RE LEDs—Four LEDs, labeled
Engine faceplate indicate the status of the Routing Engine and hard disk drive.
For more information, see Table 10 on page 16.
Power supply LEDs—Two LEDs on each power supply faceplate indicate the
status of that power supply. For more information, see Table 17 on page 23 and
Table 18 on page 24.
An air filter installed in the rear of the chassis helps keep dust and other particles
from entering the cooling system.
The fan tray contains three fans. The fan tray provides cooling to the components
installed in the router. During normal operation, the fans in the fan tray function
at less than full speed. The SCB constantly monitors the temperatures detected
by sensors and router components, adjusting the speed of the fans as necessary.
The following conditions automatically cause the fans to run at full speed and
also trigger the indicated alarm:
A fan fails (red alarm).
The fan tray is removed (yellow alarm and red alarm).
The router temperature exceeds the "temperature warm" threshold (yellow
alarm).
The temperature of the router exceeds the maximum ("temperature hot")
threshold (red alarm and automatic shutdown of the power supplies).
Check the fan LEDs and alarm LEDs on the craft interface.
, , , and
MASTER HDD ONLINE
on each Routing
FAIL