Honda Civic Owners Manual: Defrosting the Windshield and Windows
Pressing the 
(windshield
defroster) button
turns the air conditioning system on and
automatically switches the system to fresh air
mode.
Press the 
button again to turn off,
the
system returns to the previous settings.
For your safety, make sure you have a clear view through all the windows before driving.
Do not set the temperature near the upper or lower limit.
When cold air hits the windshield, the outside of the windshield may fog up.
If the side windows fog up, adjust the vents so that the air hits the side windows.
To rapidly defrost the windows
1. Press the 
button.
2. Press the 
button.
To rapidly defrost the windows
After defrosting the windows, switch over to fresh air mode. If you keep the system in recirculation mode, the windows may fog up from humidity. This impedes visibility.
Using Automatic Climate Control
The automatic climate control system maintains the interior temperature you
select.
The system also selects the proper mix of heated or cooled air that raises or
lowers
the interior temperatur ...
Synchronized Mode
You can set the temperature synchronously for the driver’s side and the
passenger’s
side in synchronized mode.
1. Press the SYNC button.
The system switches to synchronized mode.
...
See also:
Honda Civic Service Manual. Passenger's Dashboard Trim Panel Removal and Installation (Without Navigation)
8411K3
1.
Driver's Dashboard Lower Cover
1.
Remove the driver's dashboard lower cover (A).
2.
Dashboard Subdisplay Visor
...