Just a follow up incase anyone else runs into this issue: The duovalve has an internal failure. For whatever reason, this is causing all sorts of failure in the electrical system. To include the fan randomly turning on and off, climate control panel turning on and off, zeroing out of of the temperature, full heat, and sometimes full A/C. Disconnected from the system and all is working normal.

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1989 560SL
1986 300SDL
1983 300D (Burning Jet-A)
1982 240D
1995 S600