Question on wiring of 97 A/C pressure switch

A few weeks ago I posted a problem with a family members 97 V6 A/C not
working. A poster suggested removing the A/C pressure switch and
hitting it a few times because sometimes it can get stuck. Well I tried
that and it did not work, but I noticed that on the switch there are 2
electrical pins, but the wiring harness connection has 3 wires on it.
When I tried to jump the switch, I got a big spark and the car almost
died. I thought I jumped the correct pins. Does anyone know how to jump
out the switch? And what is the 3rd wire for when apparantly it's not
connected to anything.