It is not recommended to run a dehumidifier with the window open as it can affect the performance of the machine. Dehumidifiers work by drawing in moist air, cooling it, and then collecting the water droplets that are created. If you have the window open, cooler air will be drawn into the machine instead of moist air, which will decrease its ability to function properly.
In addition, running a dehumidifier with the window open can also be a safety hazard. The machine may pull moisture out of the surrounding air too quickly, which could create excess humidity and lead to mold growth or even structural damage to your home.
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