I had the *exact* same problem. I uninstalled a microsoft news app that was installed as part of an OS upgrade a few weeks ago and voila! PROBLEM SOLVED!!!
My Dell Precision M3800 laptop fan turns on for about 2-3 seconds, then off, then back on for 2-3 seconds.  This repeats every 15 minutes (exactly every 15 minutes).  And when the fan runs (loud), I can do nothing but wait because it won't accept typing, mouse moving, nothing.  Everyone in the room looks at it when this happens. I've tried making sure all Apps are closed, so the laptop shouldn't have anything requiring a lot of power, but it still does this every 15 minutes. This just started about a week ago, but it needs to go away.
Laptop Fan comes on for 2-3 seconds, twice, every 15 minutes