Constant cold air in footwell when AC is on??
Is this normal? Thanks for helping. If this is not normal, would it be costly to repair?

First try doing a system/flap reset.
https://mbworld.org/forums/c-class-w...tic+easter+egg
If this does not work it is likely a failed stepper motor or stepper motor arm. Spares are cheap but quite a bit of dash stripping is required. You are lucky you have a 240 - less stepper motors than a 320.



Your car is probably pre redesigned arms. Do you sometimes hear ticking noises?




