I found this info on a peugeot 407 website:
The bi-directional sunshine sensor helps to anticipate the effects of the sun's rays, thereby avoiding unnecessary changes by passengers to the adjustment settings.
http://www.tuninglinx.com/html/peugeot-407-coupe-07.html
All coupes come with automatic air conditioning with dual zone temperature distribution. This follows the example of better equipped existing Peugeot 407s. The air conditioning system uses modern technologies such as a temperature sensor and a hygrometer, which prevents the appearance of condensation for example. The "externally controlled" compressor can regulate the production of cold air to the exact amount required by passengers, thereby reducing fuel consumption. The bi-directional sunshine sensor helps to anticipate the effects of the sun's rays, thereby avoiding unnecessary changes by passengers to the adjustment settings.