Hi there,
I recently purchased a '79 450SL, and found the heater doesn't work. It has some vacuum leaks, which I'll fix, but the control unit is shot. ($1590). I'm looking at installing the Unwired Tools ACCII upgrade kit, which replaces the old control unit with a digital controller and more standard heater valve, and am soliciting opinions and information from those who have installed the kit. I see they have a revision that elilminates two of the vacuum valves their original kit contains (the original kit had a valve for the recirculate flap, the side/center flap, and the leg flap. The revised kit contains only a vacuum valve for the leg flap.) My question is: Does this eliminate some control function vis-a-vis the original control unit, or are the recirculate flap and side/center flaps still controlled by the original panel controls? I would think it very desireable to retain all the recirculate function when the air conditioner is running.
Thanks in advance for your helpful replies!

Richard Wooldridge
'82 300D/4.3L V6 conversion
'79 450SL - Red (What is the 1979 red called?), Bamboo interior
'75 280C