I've been reading the forum with respect to erratic heater/air conditioning problems. My 95 C280 is also blowing hot & cold air at various times with wild fluctuations of fan speed. Is the monovalve a possiblility? I checked in the parts shop and it doesn't recognize that part name. Does it have another name? Does the C series have them? Is it something I can check? How? Any help would be greatly appriciated.