What is this thing?

[agrevbuzz]

I’m working on a 76 Dart 225 slant six.
Replacing hoses because they’re old. But I wonder what is this?

Heater hose runs right through it

 

[Garrett Ellison]

Heater core flow control valve for later ac car.

 

[agrevbuzz]

Heater core flow control valve for later ac car.

thank you. So does it keep flow from happening when ac is on? Make it to where water only goes to heater core of heater is turned on?

 

[Joey4speed]

Yes.
Opens and allows hot water into the heater core inside the car when you select heat.
Should close and stop hot water flow when AC is selected.
Actuated by vacume.
(Mode doors also move under dashboard to allow hot air from the core or cold air from the ac evaporator to circulate in the car).

 

[67Dart273]

Exacto, and I could never figure why they were not used on ALL cars. The heater core radiates quite a bit of heat on non AC cars even though there is no/ little airflow

 

[moparmat2000]

Non A/C here ya go

 

[Charrlie_S]

The valve allows hot water to flow when in A/C mode. It shuts off the water, when vacuum is applied, when in max a/c mode.