W126 Climate Control Demons
 

So im in the process of repairing the HVAC system on my 82 300SD and Im a little stumped. The issue I am having is that none of the vacuum pods actuate to open close any of the flaps in the HVAC system.

So far I have:

checked for proper vacuum to the 6 switchover valves that feed the pods... that checked out fine.

Checked all vacuum pods according to the FSM...found one leak and plugged off that pod.

Next I plan to check the switchover valves individually.

But it almost seems like whatever sends the electrical signal to the valves is faulty. When I run the ac the fan blows in all settings and changes automatically in auto mode. I would expect that some of the switchover valves would work. So I guess my question is what sends the signal to the switchover valves? Is that the pushbutton unit? Thanks for any help.