The water for my sons place is supplied from a common well that will serve about four houses. Since this is a newer building area, he is the only one now using it. He has a problem with the pressure switch linkage freezing up. He has heard that there are others in the area that are having the same problem. The switch sits up right out in the open and we are thinking that after being exposed to the sun during the daytime that it draws moist air under the plastic cover when it cools down at night. It is a Square D switch. The well guy came out and replaced the original switch because of this problem and then taped some fiberglass insulation around it. That didn't help as it is still freezing up and not turning the pump on. One time it froze in the on position and built up enough pressure to pop off the relief on his hot water heater. Does anybody have any ideas on how to correct this? A couple of thoughts that we have are to try and seal up the cover so that moist air would not flow under the cover as easily. There is a lot of wind and blowing snow. Another thought would be to have some deicer or something on the linkage. He doesn't really want to have a light bulb going all of the time and it probably is 230 volts at the switch.