When you "lock" the temp wheel to the min temp detent many things happen. The pushbutton ignores most temp sensor imputs, locks the fresh air doors shut & closes the heater valve completely. Also closes the defrost flaps completely. Except on bi-level.
In the heating mode max detent, the heater valve & fresh air doors remains WIDE open. So temp sensor imputs have no effect on the heat of the air comming out of the vents.
In a normal mode the system should maintain temperature in the car with-in 2C deg of the desired temp after 8-10 minutes of operation at face level.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)