How can I diagnose whether the aux fans are working for 1995 s320. I've checked the fuse and its OK. I cannot remember a time since I've owned the car that they have ever come on. Now that the weather is hot I am seeing a periodic steamy smoke come from under the passenger side front wheel when I come to a stop. I'm thinking that it is from the overflow valve on the coolant system. Otherwise when I look under the hood I cannot find anything that jumps out as the cause of the smoke. Any thoughts?