So, this problem happened a few weeks ago when my car started making some naaasty rattling noise, so I got home and realized the fan was on high, even though my temperature was normal! It went on for some time, but it would only turn on mid-trip, not when I started the car. So, I thought that changing the relay would fix my problem, but didn't check if it was dead with a multimeter. So, I get to autozone and buy the new one, pop it, turn on the engine and the fan didn't come on. So, I drive home and mid-trip the fan comes on at high, so it definitely wasn't a relay switch problem.

But what is it? If someone could help I would really appreciate it.