Found an awful coolant leak from a broken part but I can't figure out what the part actually is. There are two heater hoses coming from the firewall and two from the engine. More or less under the reservoir, there is a plastic junction with a cable running to it the looks like it operates a plunger or something which connects the two sets of hoses. Can anyone tell me what this part is???

 

Welcome to the forum.

What year and what is model is your vehicle? Also a picture would be helpful of the part in question.

That being said, could it be a shut off valve for the heater when the air conditioner is turned on?