I have a 2017 C-Max. Bought it new. It has Blis. I live in Iowa.
When it is below 32 degrees F and I put the fan at max speed, the left mirror Blis light goes on.
When I lower the speed manually to less than 60%, the light will go out and everything is just fine.
I never have this problem at temps over 32F.
Dealer verified the problem, but cannot find a cure.
Switched mirrors, same problem.
Switched rear sensor, same problem.
Replace left door control module, same problem.
Replace the main control module, same problem.
I am giving up now since I think there is no solution for it.
Personally I think the blower motor is giving of a electrical noise that effects only the left side and turns on the mirror light.
Even in the cold, it works great except when fan in at max or near max speed and temp is below 32F.
Anyone have this same problem?