W126 380SE Vacuum Pods Inop
 

OK, here's the deal. Originally my defrost was always-on. I removed the defrost flapper pod through the glove box and took it apart - the diaphragm was torn. So I plugged the lines and put the pod away, intending to order it eventually. In the meantime I held it closed with wire, but as you know that can cause some foggy situations when it rains outside.

That was a year ago. Today I finallyl got my brand new replacement pod and installed it, but it doesn't do a thing, almost as if there is no vacuum going to it (I did cycle through the different heating/cooling/recirc [max] functions, etc. to no avail.) Interestingly, my recirc door doesn't seem to work either, and I observed it working a year ago when I removed the defrost pod.

Any ideas where to start? I would just leave it broken, but summer A/C season is coming and when the defrost flap is stuck open the A/C loses half its efficiency. If I wire it shut, I lose defrost function.

Check the vacuum switch-over valves to the right of the radio. Two of them were bad in mine, including the one that controls the defrost flapper.

raymr - thanks for the info. Pardon my ignorance, but do I need to pull the radio to get to these valves? What do they look like? Can I get to them through the glove box? Or does the whole dash need to get pulled.

Just pull the carpeted panel off on the passenger side. I don't think you need to pull the radio. The valves are metal cubes with wires and hoses attached. They are mounted on a metal strip. I just ran a continuity test on each one to weed out the bad ones.