I have a '98 model UK spec C200 auto. Recently the coolant warning light came on in the instrument cluster and the cooling fan runs continuously, albeit slowly, whenever the ignition is switched on. When first switching the ignition on, the fan starts up then cuts out, starts up and lasts a little longer then cuts out, and so on, until it finds the strength to run continuously.

The cooling level is fine as is the coolant concentration etc. The car is running slightly cool (no surprise with the fan on all the time) at 80c.

The car has been with the dealer for a week now. He is changing the instrument cluster as he has found a defect in it and thinks the problem may lie there.

I'm very wary of messing around with the dashbard and would really appreciate advice before authorising the work. My own feeling is that the problem is likely to be a defective coolant temperature sender unit or a defective cooling fan switch. The dealer says otherwise. Any helpful suggestions would be most appreciated.

Have seen the same peoblem on 2 different 1997 C230's. Instrument cluster fixed both. Also have had to replace several engine fan control modules, for that problem.