12v supply on refrigerator.

Hi, can anybody tell me what the 3 terminals are on a red 12v fridge switch (I.e. for cooling whist running)? I’ve had problems with this. At present if two terminals are connected (each has a white wire) the switch illuminates ( not sure if the fridge cools), but when I connect the third (brown) wire to the middle terminal, the illumination goes off and there is a clicking from (possibly a relay?)  near the main set of fuses.