In English, Biggles is saying that that is either a high or a low pressure switch and it's tripped/open. I can't tell from your pic but if it's a low pressure switch then your system is running low on refrigerant. If it's connected to the high side pressure line than you've got other issues, possibly a restriction in the refrigerant lines.
The switch is doing it's job of protecting the compressor. In other words you have a refrigerant problem, not a low control voltage problem.
I got your back, Biggles.