The heater in my 2012 W251 R350 blows nothing but unenthusiastic luke warm air at Maximum setting however the Aircon blows nice and cold. This is a recent change from previously working well in all states. From reading various posts I flushed the coolant system firstly to no avail and then bought a Heater Control Valve as the next most likely culprit. Having spent a while researching where the valve is, I have drawn a blank on the R class. Easily found other models though ! Can anyone help in providing pictures / a manual entry or a link to show how to get to the valve oon the R class please !