Fans, Ventilation, And Airflow - Cisco 4000 Series Hardware Installation Manual

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
Figure 1-33
showsCisco 4431 ISR airflow,
4221 ISR airflow.
Figure 1-32
Figure 1-33
Hardware Installation Guide for the Cisco 4000 Series Integrated Services Router
1-38
shows Cisco 4461airflow,
Figure 1-36
Cisco 4461 ISR Airflow
Cisco 4461 ISR Airflow (NEBS View)
Chapter 1
"Replace a Fan Tray" section on page
Figure 1-34 shows Cisco 4451-X ISR airflow,
shows Cisco 4321 ISR airflow, and
Overview of Cisco 4000 Series ISRs
5-61.
Figure 1-35
Figure 1-37 shows Cisco
OL-32185-02