Technically speaking, hot air has a greater capacity to retain moisture per unit of air compared to the same unit of cold air; that's why we get dew and frost in the shoulder seasons as the air cools overnight. The drop in temperature has a similar effect as would wringing out a saturated sponge. However, the simple act of heating cold air doesn't introduce more humidity to that air. If the HVAC controls are set on drawing fresh air from the front cowl on a dry cold day, the air blowing on the windows will be just as dry as the originating cold air coming in. If there's any precipitation, that would introduce a source of humidity that would get into the warm air, and that's when I'm glad to have the AC come on to help clear the windows.
In our culture obsessed with absurd excess, the Nissan Micra is my counterculture car of choice.
Be sure to visit my blog at
mymicra.com!
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View my fuel log 2015 Micra SV manual: 6.4 L/100 km ... 44.3 mpg (Imp) ... 15.7 km/L ... 36.9 mpg (US) ...