hello scott733i,
I am intrested in you heater issue, i have the same 83 733i, with basically the same issue(lights are on apropriatly but no selector, it worked intermittently for a short period but now there is nothing), no heater control, and stuck on defrost, only difference is my blower speed dial still works, and i belive the temp control works as well(its cold now where i live so it stays at full), but none vent selector buttons change air direction through the vents, only blows on defrost(front window only)
is this possibly a safe mode that a failed selector goes into?
just wondering if you solved your issue, I am thinking of replacing the climate control panel, but hate to go trial and error when spending money on parts.