Can you get a recording of this noise? Plus let us know if you have the same vehicle listed above. Then does the knocking noise ever stop or does it continue to do it and then you checked 3 hours later and it was still doing it?
I suspect this is an HVAC door actuator that is not performing the calibration so the module keeps moving it to try and learn its position. However, hearing it will help figure this out.
Sunday, March 14th, 2021 AT 7:15 AM