I live in NE Ohio where the heater/deicing is used a lot. On my 2017 Model X I have always had to manually turn on the defog function and have to continually play with it in fogging/icing conditions.
I got an Model S loaner that the defogging worked great. See the 2 screenshots. With the climate control on auto it would switch back and forth between 3 zone and defog only seamlessly.
My Model X has NEVER turned on all 3 zones or the defog only while in Auto. It stays on the lower 2 zones. The only way I get defogging is by manually activating defog next to the passenger seat heater icon. I pointed this out to the SC tech and tested my car and another Model X and said that the system is functioning as designed. Does everyone’s Model X require manually turning on the defog? The Climate control HVAC works great in the summer but is useless in Auto in the winter.