Great tip Donald! Twice, I had the system delay you speak of, and I thought that it was potentially the first thing going wrong in my new baby (1984 300D). Of course I immediately assumed the worst, that the control unit was going bad; but I will try your method. I will keep my fingers crossed and tap on the wood veneer for good luck.
Also, you mention that the recirculation function “is time sensitive and you need to turn it on after it times out”. I know that your 124 chassis has a separate recirculation switch, but the 123 does not. Do you by any chance know how to prolong the recirculation mode in a car without the separate switch? Or is my ignorance showing?
One of my favorite ‘tag’ lines:
Ignorance is the lack of information; Stupidity is the lack of ability to use information.