Does anybody know where the coolant control valve is for the rear heater? (Or if one exists. My 2000 Astro had one)

In this photo I took, you can see the two hoses coming from the manifold that houses the thermostat. After about a foot of rubber hose, there is a metal "T" junction. From there, one rubber hose goes up to the front heater core, and two metal lines which go all the way to the rear heater.

Maybe the rear heater core is always hot, and temperature is only controlled by diverting air flow?

2013 1500 w/rear heat + AC

 

I have the same question... Joe- did you ever get an answer?

 

yep its always hot front and rear. temp control is with blend door. no valve to my knowledge. I haven't seen one on a gm is a long time.

 

There's definitely no valve, so it's always hot. (they were unreliable anyway)
Probably to cool the transmission. See my other post here:

https://chevroletforum.com/forum/exp...e2/#post468427