Yes, AC is important because the fresh air venting in these cars wasn't great .
The W123's had passable fresh air venting but the W116's were assumed to be bought by rich folks who'd of course expect the windows up always and forever .
My first and second 300CD's were Klima I equipped and bad, really bad so I took the time to teach my self how to test, diagnose and repair them, it's a fiddly job but do - able and once finished it was like a
meat locker inside much to my enjoyment .
I sold that car during a heat wave and they guy who came from up North was amazed when I picked him up at the air port, he was soaked through his shirt in the 110* F temp and inside my Coupe it was a balmy and
dry 65* f
.
Sadly, the design aspects of the wretched
EVIL SERVO FROM HELL is such that even once you've bought one with an aluminum body (can't crack & leak out all your coolant, yay !
) you still have to be right on top of the cooling system all the time, allowing it to sit for the shortest time will likely cause the servo to jamb again, this fries the little ($!) amplifier behind the glove box and the downward cascade begins anew .
When working it's as good as anything GM (and NO ONE does AC like The General !) ever made .
There were digital up grade systems, I have one salted away God alone knows where, I never id install it .