1991 Honda Accord what part is this?

I need to know what part is this I'm losing my mind please this cable or plug is disconnected from where it is supossed to be I'm a US veteran in desperate need for an answer CB7 pros only! Pics are in link:
https://www.facebook.com/...=1&theater

https://www.facebook.com/...=1&theater

Since I'm not a pro I can't tell you the disconnected part is the radiator fan coolant temperature switch. Notice also the bleed nipple beside it; the coolant must be bled there every time the system is refilled.

Sure looks like it would be the coolant temperature sensor as that is the thermostat housing.

Thank you all I figured it was the thermostat housing duh duh… Airborne!

Well you post a picture with lots of plugs and wires can you go to like paint and make a pointer in red of which plug your referring too