either the pump runs but does not pump or you have a large leak in the system.there are two limit switches on that pump one for vacuum when locking and one for pressure when unlocking.

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
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