No "monovalves" on the 190s (Thankfully). The heater core gets hot, but instead of heated air, it appears that I am getting "vent" air out of the heater ducts. I hooked my mityvac up to all of the vacuum pods (one at a time). When I got to the one that wouldn't hold vacuum, if I pump the mityvac, then I get hot air. I have looked it up, and it seems that this is the pod for the "main air flap", that determines whether outside vent air goes to the cabin, or air heated by the heater core.

SteveM.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner