Fans, Ventilation, And Airflow - Cisco 4451 ISR Hardware Installation Manual

Chapter 1 Overview 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 fan noise. When necessary, the fans operate
at the higher speeds under conditions of higher ambient temperature. To replace Cisco 4451 ISR,
Cisco 4431 ISR, and Cisco ISR4351 fan trays, see the
Figure 1-26
shows Cisco 4321 ISR airflow, and
Figure 1-26
Figure 1-27
OL-32185-02
shows Cisco 4451 ISR airflow,
Figure 1-29
Cisco 4451 ISR Airflow
Cisco 4431 ISR Airflow
Hardware Installation Guide for the Cisco 4000 Series Integrated Services Router
Hardware Features of Cisco 4000 Series ISRs
"Replace a Fan Tray" section on page
Figure 1-27 shows Cisco 4431 ISR airflow,
shows Cisco 4221 ISR airflow.
6-53.
Figure 1-28
1-37