Your car has a number of electrical components, including switches. Thanks to these switches, you can operate a number functions like lighting, air conditioner, heater, power windows, power door lock and a number of car accessories. Through their respective switches, these vehicle functions can be turned on or off, or even adjust their strength or intensity.
Regardless of the vehicle function they operate, all electrical switches – like every electrical component -- aren’t supposed to get in contact with water as they would get damaged. When switches gets wet, it could result to wiring shorts, shorted switches, blown fuses, fire, or corrosion on contacts and wiring.
Water isn't really what damage -- aside from rust or corrosion – electrical parts. Water itself is considered as one of the best insulators of electricity, which mean electrical current can’t travel through it. However, there are small particles that dissolved in water – called ions – that cause electricity to go to places where it is not supposed to go. This is what causes a short.
There are situations in which your car’s switches can get wet. For instance, you might have left the window a bit open while driving in the rain or snow. Or, you might be drinking water or holding some drinks, and accidentally, the liquid got into the switches and made them wet.
As soon as you notice that a switch in your car has become wet with water, remove the liquid as quickly as possible to prevent it to penetrate into the contacts. If a switch if left wet with water, the liquid may trickle down to the electrical parts inside and cause some problems.