Does flow to the heater core ever fully shut off?

[speedoflife]

Does anyone have knowledge of the inner workings of the heating system?
Is there always a small amount of coolant flowing through the heater core? Or does the coolant flow shut off when the A/C is set to the blue side? Do you have to turn the fan on to open up coolant flow?

For example, if I'm cruising around with the temperature set to the heater (red) side, but have the A/C fan OFF entirely, will coolant still flow to the core? I tried googling this question but could find nothing definitive about our cars.

 

[2000GTSTANG]

There is no valve on the heater lines; so coolant is always flowing to the heater core.

 

[P49Y-CY]

No, there is always coolant flowing through it. The temp blend is operated by the door.

The core is downstream of the evaporator, which is why it is important to never run the ac if you are running straight water.

 

[speedoflife]

Awesome - thanks for the info guys. Good to know that coolant can always get out of the back of the passenger head at least.