It is supposed to turn the fan off and close the lid automatically if the sensor detects rain. Mine have not been tested in real world conditions yet because as the song goes "It Never Rains in Southern California," but I did hit it with a light spray from a garden hose and it works.
Bubba & Chiquita + Two Vizslas (Barley and Sophie)
2008 Georgetown 315DS SE LTD
2011 Jeep Wrangler Unlimited Rubicon
Sterling All-Terrain Tow Bar - SMI Stay-In-Play Duo
Do What You Like - Like What You Do!