Okay, I just got the radiator and shroud out. I noticed a plug sort of tucked out of view behind the thermostat. When I pulled it out, I could see that it appears to belong to this thing on the right, which is also blue. What is this, and why would someone disconnect it? Like is disconnecting it a way of cheating the car to act a different way, or run better (indicating a different problem altogether), or of course could it possibly have just been overlooked and forgot to plug it back in.