Where does the brass wire go that's attached to bottom of ac box? I'm thinking it goes to the temp mechanism on firewall but I cant see how it attaches.

water valve on the firewall

Great, any one have a picture of how it connects to it. I tried every hole on it and it won't fit any where. I must be missing something.

realize this won't be lots of help, but here is a picture with the copper line coming back to the water valve... it's the one on the left side of the valve in the picture (not the right which is the mechanical temp control switch)

i don't remember but the copper may terminate at a thermostatic coil winding possibly????