We have an '08 328 xi with 21,000 miles, and about a month ago, in temperatures of about 50-65 degrees F., the radiator fan started coming on, without air-conditioning on. I could see it if it were really hot out and the a/c was on, but neither was the case. Brought it to dealer, and they said all was normal. Just about every car I've owned in my life has had a thermostatically operated fan for the cooling system, and I have never had one come on at such light duty. Mind you, I live in the Boston area, and it's really pretty flat, so it's not tough grades causing this. Of course the car DOES NOT have a temperature gauge so I can not tell you that spec..... really dumb BMW on that one!

I think it's a partially open thermostat, but how can I be sure? I do have one of those laser thermometers, but don't know what I shoulfd look for 220 degrees?

The coolant is quite full, and I did top it up about 6 mo. ago with BMW anti-freeze coolant. This did start in city driving conditions, about 90 minutes of steady stop and go city driving in a large metro area. But this was late winter/early spring outside temps.

Anybody else have this issue? What would you do? Get a factory rep involved?