A/C compressor not working properly

I am having hugh issues with the A/C. I bought it when it was cold so I really didn't pay attention to the A/C but now i've spent over $2,700.00 trying to get it fixed and it's still not working. I've replaced the evaporator core, A/C accumulator, freon, upper and lower hose clamps, fuses, and the A/C compressor. It's still not working. I got all my parts from Napa. They have given me the wrong part 2 times. I had it working for about a week then the A/C compressor went out. I've replaced it 3 times. The last time I replaced it they gave me an A/C compressor with two sensors on it which was kind of weird because the previous two other ones didn't have 2 sensors on it. So now the compressor isn't working at all. Napa said it's the same part number as the previous two other ones I bought. So my question is, does the front A/C compressor have one or two sensors on it? And if so does that mean I have an electrical problem?