1986 420sel electronic temperature modulator?

[gmbreit]

Pre 1986 there was an electronic temperature modulator....metal box...about size of a pack of cigarettes. But I can't figure out if my 1986 has one of those things. My Klima monovalve seems to be stuck, but the Klima people told me to get a new temperature modulator. I am not sure if such a thing exists, and I am not sure of where it might be located. I did get a new blower regulator, similar little box....but I am confused about the temperature regulator.