72 chevelle thermal switch getting red hot

my thermal switch on my a/c is melted and when i run a jumper to it it gets red hot, im unsure if its supposed to do that , 1 wire is melted and i need to resolder it on the switch. anyone know if its supposed to get that hot ? im low on freon and adding some to it this weekend .ive read that it will cut the ac off when system is low but getting red hot ?????