수리 사례

2026. 6. 30. 작업

증상

Is it okay or useful to run heat and AC at the same time?

처리 내용

You're meant to. In fact, in older cars, it was automatic when redirecting air to the window defroster. On this GM control, the far right position would activate the A/C compressor. Almost always, it is a cold, wet day, and you have both sliders all the way to the right. The pass across the activated A/C coils dries out the air, because of the way humidity works. So your window glass is immediately hit with dry air, and there is no need to wait for heat to become available. Later, as the engine warms up, the heater coil becomes effective, and now you are getting air that is pre-dried and then heated , which dries the air further. This dryness, moreso than the heat, defogs all your car's windows. Humidity and the battle for your windows The way humidity works is that warm air can hold quite a bit more water than cold air. That's why they talk about "relative humidity" instead of absolute humidity in terms of comfort. So if you have 10C/50F air, it won't have a ton of water to begin with