What is this(coolant system leak)?

[apoctank]

2006 explorer limited 4.6 w/ 3rd row climate
I have been leaking coolant from some heater hoses on the passenger side. It looks like it's either coming from this piece pictured or from the hose directly underneath it. I was curious what this was called so I can possibly order a replacement. It has a spring loaded mechanism similar to an old school mechanical throttle

 

[Rcflyer330]

I am pretty sure thats the heator control valve. It uses vacuum to shut off the coolant flow to the heater core when its not needed.