I have a 2000 C280 Sport. I've noticed my heat wasn't producing the heat that it once did. I do get some heat but not as hot as it was. I just changed the thermostat and flush the coolent with all new G05. I'm still having the same problem except I do get heat then I would get burst of cold air, then back to heat (but not the same as before). Obviously, I think I have another problem. I did also purchased a coolant temperature sensor but haven't installed it yet. Wondering if this would solve my problem? or is there something else I'm missing. Needs alot of feed back soon because the temp here in Wisconsin is ready to drop to single digits in the next few days. Thanks in advance to all who reply.