Hi, This is my first post on this forum so I hope I'm posting to the correct location? Anyway I have a W212 Estate and the heater will not blow air out into the car but the heater indicator shows that it's on. Now I've had a quote on the parts from my local Merc garage and they have said that the heater fan motor and resistor will cost £580 then there will be a fitting charge. Instead of just buying the parts how do I diagnose which part is at fault to reduce the cost? Also, the Mercedes garage won't tell me part no.s so it's a wild guess as to whether I'm buying the right ones if I go to a third-party parts shop. any suggestions?