W124 aux fan issue.....I read tons of posts

[Q-Ball]

Been a while since I have posted, been restoring a BMW 2002 for autocross this past year.

I know you guys have the answer.

1993 W124 165K. Perfect condition, everything done to it. I may drive this car 2k a year now, was daily driver for a decade.

Problem--At start up, aux. fans no longer operate, which they are supposed to for a short while. Once vehicle idles for a while, temp. goes up, and high speed fans will not come on at 100-107 mark. If I turn on A/C, both fans kick on. If i unplug 2-post, blue switch on thermostat housing...high speed aux fans kick on...i plug it back in and the fans shut off.

What am i up against? I have spare fans to replace the others. Should i be concerned over an electrical issue, at thermostat? O rjust pop in new fans.


Thanks again everyone.

FQ