HP ProBook 655 G1 Notebook PC - Manual (Page 24)

Component Description
(2) Service door release latch Releases the service door on the computer.
(3) Service door release lock Locks the service door.
(4) Vents (3) 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.
(5) SIM slot (select models only) Supports a wireless subscriber identity
module (SIM). The SIM slot is located
inside the battery bay.
14 Chapter 2 Getting to know your computer