The operation of the valve is backwards from the washer or dishwasher.
Energized = block, de-energized = pass.

This is done for failsafe purposes. Total system failure = max heat, max fan, default to defrost. That is because all other system functions are comfort based but defrost is safety based.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Typical Benz thinking, logik.

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Cheers!
Scott McPhee

1987 300D