well it could be because of the heat. if its cold out and you have the heat on in the car, then you will get hot and that will cause the window to fog.
moisture from your breathing for example condensing on the cold glass
It is called condensation, warm and humid inside, cooler outside.
Windows fog because the glass is cold and the humidity is high inside the car. It has nothing to do with the age of the car. Try turning the fan up to circulate the air better, and if that doesn't work, turn the AC on -- but turn the heat up so it doesn't get cold. That will do it for sure.
Rub them with soap then clear the soap of with a cloth or paper this will reduce the amount it wil fog in the future as well.
No the blend door not functioning will not cause fog; it may however prevent the windows from being defogged or defrosted. If the widows only fog up when the defroster is on, then you either have a coolant leak in the heater core or your air conditioner compressor isn't working (the AC is used to dry the air when the heat is on).
It will fog up with moisture, the inside windows in the car, also accompanied with the sweet odor of coolant.
heater core is going bad.
Well there is an easy way and a hard way, first, you could only do whatever it is you are up to in the winter, it will be colder and when you blow on the windows mist or fog comes up, or you could boil a kettle in their. Hope you got a backseat and a boyfriend or a girlfriend ; )
check owners manual i think its a bad design in which this model requires the a/c to be on at all times that the defroster/defogger is on, otherwise the windows will fog up this is horrible while its rain during warm weather
the car's a/c must be working to remove humidity and do not use re-circulation setting(max a/c setting). if your ac isn't working then make sure rec is off and the interior is dry. -awautoglass.com
If the heater core is ok, check to insure your ac unit is working. The ac works in conjunction with the heat when running defrost, and without the ac air windows will fog up .