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Discussion Starter #1
The beginning of the saga was slow engine shutdown. Analysis showed that the seat back locks were not operating. Solved in a separate post. After the seat back problem was solved the vac system generated 15 inches of vac on several tests. Following day, cooler temp, O vac in the accessory system. Because the ambient temp was lower than set reference temp and the defrost system was activated. Found a leak in the defrost system testing from the No1 switchover valve just ahead of the climate control module. Couldn't get hand vac reading. The defrost pod is a dual Y vac connect. Perhaps not enough hand vac to actuate? Disconnected the No 1 switchover valve closing the valve and aux vac returned quickly to 15 inches. Purchased the valve from AutohausAZ. Followed the MB instructions, remove underdash driver side cover. Simple instructions but not easy to follow because of access restrictions. Plus removed the instrument cluster, disconnected with difficulty the air duct and engine shutoff valve lines. I attempted to unlock the pod repeatedly and failed repeatedly. The valve is held in a steel "O" adapter with three plastic clips and secured by a plastic locking device. Finally stuck a screwdriver between the adapter and pod top and broke it out. Likely the MB procedure as rebuilds weren't done. The rod pod to flapper is retained by a plastic pin with a slit. Squeeze with needle nose and wiggle and it came free. Installation reverse and easy pod install because the lock is much less substantial than the original. PITA to hook up the duct. If the engine shutoff lines are removed, note which goes where. And the cluster reinstall is a problem for me.
Next is a retest of each pod and each switchover valve.
 

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Discussion Starter #2
Found a vac leak No2 vac line out to foot flap element. Both the defrost and foot elements are accessed by removing the underdash cover drivers side. Tested the foot element directly and good vac without leak. Told me that the leak was the three inch hose out of the No2 switchover valve. Replaced and vac tested ok.
In subsequent vac tests engine running after overnight wait, vac measured in to the 4 way T (coupe w/seat back lock) would build to 15 inches vac, 750 RPM, climate control set EC in 15 - 35 seconds including seat back lock. It takes longer if climate control is off. Engine shutdown is quick. Before repair it took 30 sec.
 
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