Yesterday evening, four adults onboard, the ambient temperature was about 5°C dropping to 3°C and triggering the ice alarm. I noticed that my auto main beam was not working although the dashboard indicator was on. Thirty minutes into a one hour journey we stopped at a shop and I saw that the windscreen sensors were steamed up although by this time the windscreen was clear. Although the aircon was on, I suspect was not working due to the low ambient temperature as the windscreen was lightly misted for while after starting the journey. A few minutes after the stop the auto main beam started working and when I got home the sensor misting was 90% cleared. I assume the other functions using the windscreen sensors were not working either.
I vaguely remember this being mentioned on here before but can't find it.