Just general info on the vacuum pods that may be useful.
Check out this link, a thread in another forum specifically on 124 vacuum pods for the HVAC system.
Spoiler alert - as you read through the tread you will see that in the last 2 years several of the pods are NLA.
I was reading this thread in real time 2 years ago, and decided to source new pods for all 4 of my 124's, and I was able to get them all, including the parts to rebuild the center vent pods.
I haven't done anything with them yet, they are all sitting on the shelf for when I get more time.
I need to change out the pods in the 94 E420 first, at least 3 of them are not working right, and the center pod on my 92 Bornite 500E isn't working.
Hopefully Mercedes may do another run of these critical parts some day, or a aftermarket company will.
I'm still in favor of the old fashion controls that used manually operated cables to operate the flaps. They never break and will out last the car. I really don't need a thermostat to maintain temps, easy enough to manually set controls. The last car/truck I seen with manual heater/AC controls on was my old 94 Pathfinder, they worked perfect, never failed and if a cable was to ever fail, any old generic choke cable could be modified to fit.
All these USA Mercedes features are nice until they stop making replacement parts for them.