Hi, '86 420: I removed the wood panel with the climate control box, there are 4 black wires with brass ends which do not stay with the harness plugs when you unplug them. I know one of the wires goes on the top of the plug on the switch on the top passenger side of the panel (turns on the rear interior overhead lamp); I found similar homes for two others but I have one "extra". What do these wires do, and where does nr. 4 go? I thought maybe they were for the night lights in the switches, just a guess.
Also, I was looking for the reason heater air does not flow out the footwell vents, I saw a device immediately behind the panel, fastened to the heater-evaporator box; is this it? It did have a vacuum line (red) going to the switchover valve; nr. 4 port if I remember correctly.
when I start my car and turn any climate control function on before the engine has warmed up, a rapid, random clicking comes from underneath the dash: switchover valve? If I let it warm up a little before turning on a climate control function, it is silent.
One of these days I'm removing the entire dash, just so I won't dread it any more.