Uncanny!I've not had any issues with my car steaming up. I always drive with the climate control on, most of the time it's set to 21, except for really hot summer days when I drop it to 19 or so.
I never switch my air con off. It seems my passengers steam the car up. I must make them hot under the collar.Uncanny!
I do exactly the same. 21C with occasional lower temp. To be honest, it's ideal and it is never off. And that may be why the car NEVER EVER steams up.