Sorry i overlooked that you mentioned the aux fan.
I am not sure whether it was running at high speed. I did not check. now that you mention it i remmember hearing it come on as i started the car after stopping for a few minutes to pick up groceries. My mechanic tells me he is going to check the thermostat. Any advise on anything else i need to check will be helpful.

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300CE 1989 Euro Model.
ML350 2011.