The big air conditioner at church wasn’t working right. The second compressor wasn’t turning on, and we couldn’t figure out what it was. Pressing the contactor on the relay powered it right up, so it was wired right. And Loran bypassed the low and high-pressure cutoff safety switches, but it still wouldn’t turn itself on.
So we found the wiring schematics from Carrier. The high power stuff was wired correctly. Problem had to be in the low voltage. So we traced compressor 1’s control wiring from the thermostat connections through the pressure switches, and did the same with compressor 2 (minus the now-disconnected switches). Everything seemed to be correct, except that the incoming low voltage for C2 wasn’t powered.
So we traced a little further, and found a broken jumper in the economizer unit that was constantly calling for outside air, and also thus not energizing the second compressor. My father the soldering gun guru did a little magic on the resistor wire, and C2 powered right up.
Back in the summer of ’95, I had a crazy little summer internship for NAVSSES, the Naval Ship Systems Engineering Station, at the Philadelphia Navy Yard. I worked for the boiler control division, doing electrical diagrams for steam boiler and turbine control systems. And now, 15 years later, it finally pays off. Turns out I can read an electrical diagram.