Seat ALHAMBRA Owner's Manual page 168

166 Heating, Ventilation and Air conditioning
WARNING (continued)
Never use recirculation mode for long periods as it does not refresh the
air inside the vehicle.
If the cooling mode is switched off and air recirculation mode switched
on, the windows can mist over very quickly, considerably limiting visibility.
Switch air recirculation mode off when it is not required.
Caution
Do not smoke when air recirculation is switched on in vehicles with a climate
control system. The smoke taken in could lie on the cooling system vaporiser
and on the activated charcoal cartridge of the dust and pollen filter, leading
to a permanently unpleasant smell.
Note
Air recirculation mode switches on to prevent exhaust gas from entering the
vehicle interior when it is in reverse and while the automatic windscreen
wash and wipe is working.