Humidity Sensor Control
WARNING: This page is about a different car, the 2008 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
The A/C control assembly detects the humidity in passenger cabin when the A/C is turned on, utilizing the humidity detection function of the A/C room temp. sensor, and if needed begins to dehumidify the cabin to create a comfortable environment.