crack a window

Atleast you have a car

Every time. And I'm halfway through life. I could do a web search, but who ever thinks of that except when this happens? Will I do a web search now? No. I have other stuff to think about. And so it goes.

When I press the defrost button in my car, it turns both the heat and AC on at the same time. I assume this is to remove water from the air with the AC, then warm up the air increasing its capacity to hold water with the heat.

67^o^

Always use heat. Anytime you have a fogged up window heat will cause that moisture to evaporate. Cold will always make the window cooler which causes more condensation.

Clean your window.

The fog is moisture condensing on the cold windshield surface. Use heat directed at the windshield with AC on. The AC dries out the moisture and the heater warms up the surface preventing additional condensation.

Temp isn't as important as ac

Remember to pull your sun visors down. My AC doesn't stay charged so I have to rely on heat alone to defog windows. The visors trap the warm air.

Whichever of the AC/Heat is on, just switch it to the other one. Or turn it off. Or open the windows.

If your windows gets foggy you need to turn up the heat as that lowers the relative humidity and direct the air towards the windshield, also check below the floor mats for water. If your car is a swimming pool your windows will be foggy forever.