Originally Posted by fk186
Very interesting thanks for the answer. So our next question is what senses the rain to indicate the high speed?
There is a humidity sensor so I guess that must be it. The fan is actually always running, just kicks in to high speed at stops or very low speed much like running the A/C in the summer.
I'm not 100% convinced but enough so not to worry about it anymore. I'm still a little surprised we are the only ones to comment on it, I posted this in all the durango forums and some other mechanical auto sites.
Anyway I'm on to the next problem to ponder. I keep having to refill my power steering from the min mark every 4,000 miles. Not visually leaking anywhere so I suspect it's slowly filling up the boots and will eventually show a leak.