w140 a/c question

[peet230e]

Guys, this is the final problem with my s500, touch wood! with the a/c on the evaporator tends to ice up on long journeys, i.e hour or longer. The solution I use is to activate ec mode until the airflow trough the vents normalize plus minus five to eight minutes and then switch the a/c on again.

I know it is iced up because the airflow gets lower and lower, and should the compressor of and just blow air there is a lot of water comeing from evaporator drain hoses until the evaporator is"defrosted"

Could this be the tempreture sensor inside the evaporator or the climate control module?