Noticed that the aux fans of my 1990 300SE turn on when the engine is at normal operating temperature of 80*C with no AC. This happened in the last three days, any suggestions of what could cause this? Now that I think of it, it started doing this after I ran the AC for the first time since the summer.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).