So is the little lever supposed to pull in towards the vacuum pot when you crank the heater up? Mine doesn't move at all. I mean it moves but just by me manually pushing it. If I let go it immediately snaps to the position as pictured.

Next, what is this contraption the valve is hooked to (second picture)? According to Rave, it's a vacuum switch but how does it work? I know the vacuum line looks mighty suspect but it's an odd size or something, I couldn't find a replacement in my short search that fit properly. I trimmed the ends though and it still seems pliable enough.

 

See attached.

 

Ahh, so it is normally open and only actuates when the temp controls go to full cold. I guess that makes sense.

While I was fooling with it I was noticing the hoses get plenty hot but the return line from the heater core didn't seem that warm. Could be an issue with the HC I guess. I need to let it get thoroughly warmed-up and make sure the coolant system is completely burped. I really don't want to do a heater core...the last time I did one on a 'modern' vehicle I swore I would trade it in or sell it before doing that job again.

I think when they build vehicles these days the very first part on the asembly line is the heater core...they build the remainder of the vehicle around it as it progresses down the line. ;-)