start the fooker up and check to see if the center of the pump is turning.. if it is then you got power to it. which means you have pressure and the switch is working. or you got no pressure and the switch is fooked or the relay is fooked.
Not being funny m8, but how do you know it isn't leaking if you haven't checked it? if its low on gas it will still get cold, its a warning, and you didn't say on your original post that you have just gassed it up either
What have you done recently to it then, its hard for all of us just to guess what you have and haven't done