The underhood module/valve that is usually the fail point has not been available from Chrysler or Mercedes for quite a few years. The was a company making an improved version of that module/valve (CAM???) might still be available, but I don't know the source. Looks like someone eliminated the valve altogether, which is why there is no heat or air.
Someone will certainly pipe up on who makes (or made) the aftermarket valve. It was a great solution to the crappy factory unit, to be sure.
View attachment 586047