2002 E320 climate control can't get out of economy?

On my 2000 E320 it was due to a sensor and control module gone bad. Had it done at a dealer so cost about a grand. Worth it after spending 1 summer on So Cal freeways during 1 hour commute...each way. 13 months later the blower motor regulator went out...it was three-fifty. Ah, the life of a Mercedes owner. Good Luck.