So, your goal is to reduce relative humidity in the air, most probably to reduce window fog or misting. Those of you looking into purchasing a dehumidifier might already know that the A/C is rather effective at drying out the air inside a car. In fact, when the defroster fails to provide results, the A/C will often succeed in its place. The evaporator coils in an air conditioning unit will get rid of a lot of moisture in the air, so why use a dehumidifier?
Time and Energy
The bottom line is, a car dehumidifier doesn’t use up precious gasoline to function. This delays that dreaded trip to the pump for just a little longer. Also, the car does not have to be on, and you don’t have to be in it, for a dehumidifier to work. For non-electric versions, just drop it on your dashboard, lock the door, and come back to a dry car.
There are times when turning on the A/C will temporarily release more moisture in the air, which can result in more intense and sudden fogging. This is caused by liquid, often water, pooling inside of your air conditioning unit. Many of us have seen the water pooling, and then dripping off of home window A/C units. A similar scenario happens in your car.
Sometimes it’s Just Too Cold
Turning on the A/C in the middle of winter isn’t the most effective solution when it comes to dehumidifying or defogging your car. The heater and defroster will do their job more often than not, but when they don’t, it’s best not to have your conditioner simulate outdoor conditions.