I wanted to verify the testing of the yellow vacuum switch for the door locking system on '83 Mercedes 240d. On the inlet are you supposed to be able to suck and not blow? It shows both of the outlet connections blocked of and then holding a vacuum with a hand tester. Does that tell you it is ok? Mercedes Source says you are not suppose to be able to suck and blow. If so, the valve is defective. If it is defective, will it cause a vacuum failure for the door locking system?

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Rebe