AC Heater Dual Valve Replacement
 

Is it necessary to flush the coolant when replacing the Dual Valve? If not do I need to bleed the coolant after replacing? My car is a 1999 C280.

Thanks for your help.

Nah, shouldn't have to do any of that to do this job. Put about as much as you think you lost into the tank, then road test the car up to operating temp with the defroster on and you should be good. Recheck you coolant level afterwards, and maybe after a day or so.
Gilly

replaced mine just a few months ago and lost maybe a cup or two. just filled back to the necessary level.