I've been working to get my heating and A/C right. ('94 740iL)

Here's the current state: I'm getting heat from the driver side (only) defroster when I shouldn't be. If I switch the A/C on, the "flap" closes and the flow of hot air stops. If I dial in a temperature that would call for heat, I correctly get heat from the other vents.

I've replaced (w/new) heater valves, resoldered the 120 ohm resistors in the control module, removed dust/lint from around the cabin temp sensor, installed a fresh microfilter, used contact cleaner on micro-switches in dash control unit.

I'm looking for advice on what to try next.
Thanks!

I removed my center control unit(part with temp dials and blower dial) with a used one and that fixed the problem for about one week. I replaced the used one with the original one and have not had a problem for 4 months. I think? the problem is a dirty connectors. Having plugged and unplugged the unit several times it cleaned the connection. Just a theory.

Morty K.