HP ProBook 4340s Service Manual page 28

Component
(3)
(4)
20 Chapter 2 External component identification
Service door
Vents (2)
Description
Protects the hard drive bay, the wireless LAN (WLAN)
module slot, the WWAN module slot, and the memory
module slots.
CAUTION: To prevent an unresponsive system, replace
the wireless module only with a wireless module
authorized for use in the computer by the governmental
agency that regulates wireless devices in your country or
region. If you replace the module and then receive a
warning message, remove the module to restore computer
functionality, and then contact support through Help and
Support. On Windows 7 models, contact technical support
through Help and Support. On Windows 8 models, from
the Start screen, type help, and then select Help and
Support.
Enable airflow to cool internal components.
NOTE: The computer fan starts up automatically to cool
internal components and prevent overheating. It is normal
for the internal fan to cycle on and off during routine
operation.