Do you mean that with the selector switch in the off position, the valve is closed so that no water flows into the core?
That picture helps a lot. On mine, the pot's bracket is screwed into that panel but that panel is floating around loosely in the case. Is that side of the case another piece that's screwed in? Like TylerW said, a picture is worth a thousand words. Here's a pic of the engine compartment with the areas in TylerW's pics. You can see my consternation when comparing them. Don't know what the blower motor came off of but it has 2 parallel spade terminals and looks fairly new. If works but sounds like the wheel is trapped, squealing loudly. I'll know more when I get it out. And, as you can see, the vacuum lines in the firewall are missing. That line you see coming out of the hole is a Sunpro aftermarket temp gauge I installed until I can get all the gauges working. I found a bunch of stuff in the trunk including a rats nest of vacuum lines, 2 vacuum amplifiers, an exhaust manifold, old EGR valve, etc. This is typical of the sins of the PO that I've encountered since I got the car. I'm sure, when I get to it, the switches, vacuum lines, cables and such on the interior will be the same.