Ron D. wrote: " DEFROST - when there is ice or snow on the windshield

DEFOG - When there is water on the inside of the window. The Dew point determines when this occurs. Lowering the humidity of the air increases
the heat capacity of the conditioned air and raises the dew point. "

Thanks for that detailed explanation. Most car climate controls
abbreviate it to "DEF", and I always assumed it was short for
defrost.



"It's hard to get people to use the AC and Heat at the same time especially when it's cold out and you want to get warm. From a Thermodynamic view,
it doesn't work."

Again, what I wrote were the suggested temperature knob settings
for defrost/defog/de-what-ever. For Heat and AC, the temperature
knob positions should be obvious - although my particular owners
manual suggests setting temperature knob to approximately the 10
o'clock position when using the Auto climate feature for cooling in
summer, and 2 o'clock for heating in winter. I followed the instructions
for Auto in summer and so far, has been transparent and satisfactory.



"See, I use thermodynamics in everyday life. Hot water freezes faster than cold water does. Ice expands when cooled. Increasing surface area increases
heat loss. A hat will increase body temperature significantly, A hat prevents heat loss from your head. layering clothes is important. I somewhat regulate
sleeping temperature by wearing one, two or no socks to bed. A bare foot in a slipper with an air gap will be warmer than a slipper, and a tight fitting sock.
Wet clothes are bad when trying to stay warm. "

Nice tips. So it's the air between skin and clothing, and between
layers, that keeps one warm.