Hopefully this will help to clarify any confusion..
In auto mode ( or Ambient Temperature Automatic Mode )...
To obtain and maintain the temperature selected and to maintain good visibility the system controls....
The fan speed
The distribution of air
The air recirculation management
The Air conditioning ( auto on or off )
The temperature of the air to the left or right
The automatic operation of the rear screen de-icing/ demisting and / or windscreen ( if fitted )
In manual mode
You operate the rear screen demisting using the demist button - When the screen is on -- the orange light is visible -
The rear screen will automatically turn off after a set period of time to avoid overheating and or battery drain..
Manual Air recirculation note
This is the circular button at the right of the climate control panel..
Air recirculation allows the external atmosphere to be isolated ( e.g. driving in polluted areas ).
Prolonged use of the air recirculation mode may cause the windows to mist up or lead to odurs as the air is not renewed.
Renault therefore advise you return to normal mode ( external air or automatic recirculation ) as soon as you can.
All info taken from 2001 Laguna Handbook..