Do you get heat when driving, but not when stopped? If so the Aux pump is out. When you are driving there is enough flow from the mail engine driven coolant pump to run hot water through the heater core as long as the mono valve is opening.

Do you get heat in the defrost position? My ACC is going bad. Right now the only place is get heat is in the defrost position.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.