The laser temp guns (20 bucks at Harbor Freight, not much more other places) are excellent for diagnosing stuff like this.
I will tell you what became my best use for a laser temp gun. I used it for battery draws. Whatever is causing the draw will be warm. You can even run it over the fuses to see which circuit is warm. Very handy. The handful of snow was for showboating.
But I, for one, would never buy any tool at Harbor Freight.