What possible wires could be bad, leading to my AC compressor? on 2006 Kia Sorento

I had a new AC compressor put in my '06 Sorento after recharging the old one and it still didn't work. The new one doesn't work unless hooked directly to a power source, leading me to believe wiring is involved. What is the best way to find out which wire, if any, is the cause?

Asked by for the 2006 Kia Sorento