The wire right from the dash switch out to the high pressure switch that turns everything on is most definitely 12v. My meter said so when I checked it, and as connected above to the positive side of the relay coil with a negative on the opposite side it does turn on the relay.

If in fact I'm missing something and you are correct, the relay shouldn't be turning on and enabling the compressor, right?

Regardless, the other side of the relay coil is grounded through the stock "cycling switch" that is on the accumulator, and it isn't turning the compressor on and off. Regardless of whether I'm putting 12v or ground through it, that switch isn't disconnecting and turning off the compressor based on pressure and that's what I don't know how to fix.

I've been told that I may just need to use a low pressure switch form something like a 88 truck that only uses that one switch for cycling, and that one should then turn the compressor on and off? It was said that maybe the stock 98 doesn't simply connect and disconnect, but it is actually just varied signal since it originally went to the pcm, and that's why it won't disconnect it's side of the coil to cycle the compressor. I have no verification for any of that though