The automatic climate control is designed to be set at any comfortable setting & left there. The whole idea is that you don't have to reset the temperature all of the time. There is a sensor in the dome lamp area that is responsible for most of the temperature corrections, possibly it isn't doing the "job"!! Are you using the "EC" mode alot?
MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH