Electric Fan/ Radiator Sensor Help!

[driftinstinct]

So I bought a s13 from Mr.sketchy. The car has been running fine, but I noticed it starting to overheat today. Upon further inspection, I found my electric fan wasn't kicking on anymore. It had been working fine up until this point, and it would even work in conjunction with my turbo timer. So I looked under the hood and I found this! It looks like my sensor is just floating around in the engine bay. I played with it today a bit and got the clutch fan to turn back on for a moment. Where/how do I properly install it?!?! Also, what's the technical name of it? Any help would be greatly appreciated. Let me know if I posted this in the wrong section!