I just went to turn on my Central air this week and the outside unit is not turning on. It looks as though the red power wire leading into the fuse box thiat is on the side of my house had a cut in the outer lining and has arced on the ground as there is a big brown mark like a big spark had gone off. The swith in the outer power box is able to be reset though. So following the power from the fuse box to the A/c unit itself I see that it leads me to this part # B13603-21 which has an odd little part in the middle on a spring that you can push in and it springs back out. This is the part I am not sure about. How do I know if it is bad.

The part you are talking about is a contacter,, it should pull in by itself when ac ic turned on, if it is pulled in and still yet nothing is working, you can check out the top part of contactoer with a volt meter,, be careful you are messing with 230 volts of electric