no spark after vintage air install

[evilokc]

I work on my truck a lot but its rarely a mechanical issue. I finally got the a/c system wrapped up. it was cooling well in the garage. I headed to the gas station and then my first car show if the season. got about two blocks and turned on the a/c and the truck died. no spark. got it fired after 30 minutes. huge backfire. didn't make it home. was about 100ft short and pushed it the rest of the way. put a spark tester on and it has none. ive read that the vintage air systems pull a ton of amps. im hoping that the draw from the a/c and electric fan on the condenser was just to much for the old coil. anyone ever have this happen or have suggestions?