Cisco 4000 Series User Manual

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Hardware Installation Guide for the Cisco 4000 Series Integrated Services Router
OL-32185-02
Chapter 1 Overview of Cisco 4000 Series ISRs
Hardware Features of Cisco 4000 Series ISRs
Fans, Ventilation, and Airflow
Chassis Ventilation
Router and chassis temperature is regulated with internal fans. An onboard temperature sensor controls
the fan speed. The fans are always on when the router is powered on. Under most conditions, the fans
operate at the slowest speed to conserve power and reduce noise. When necessary, the fans operate at
higher speeds under conditions of higher ambient temperature. To replace Cisco 4451-X ISR,
Cisco 4431 ISR, and Cisco ISR4351 fan trays, see the “Replace a Fan Tray” section on page 5-61.
Figure 1-33 shows Cisco 4461airflow, Figure 1-34 shows Cisco 4451-X ISR airflow, Figure 1-35
showsCisco 4431 ISR airflow, Figure 1-36 shows Cisco 4321 ISR airflow, and Figure 1-37 shows Cisco
4221 ISR airflow.
Figure 1-32 Cisco 4461 ISR Airflow
Figure 1-33 Cisco 4461 ISR Airflow (NEBS View)

Cisco 4000 Series Specifications

General

Brand	Cisco
Model	4000 Series
Category	Network Router
Language	English