2008 F-250 with the dual zone EATC system. I'm getting intermittent knocking/buzzing/whirring from the dash area, and everything I have read seems to lead back to issues with the blend doors and/or actuators. I performed the EATC self test, but no codes were shown, and the noises still persist. I was hoping the system would tell me which of the doors/actuators are faulty, but no such luck? How do I know which one(s) to replace? I'm ***-uming there are more than one, to control the various blend features? Thanks for any info!!

 

Ford/Rotunda IDS with a VCM2 would do the trick.
It should be able to command all of the motors to move.

Sean