07 Burb A/C has charge but won't turn on

[NastyNate98]

I have a 2007 Suburban 2500 6.0 and I can't get the A/C to turn on. I have A/C gauges, a charge bottle, and a power probe to test fuses and relays. I have replaced the low pressure switch and the switch (high side switch?) near the Compressor. I can function the compressor ON with my power probe by jumping the relay, so I know the compressor clutch works, and I can feel the air get cold. Something is not switching the A/C on and I thought it would be one of the switches I replaced. The truck is quite rusty, so maybe there is a ground somewhere all rusted out. Does anyone have a wiring schematic for the A/C system for this truck? Thanks

 

[NastyNate98]

Pulled the compressor relay and tested the 4 pins. Was missing a ground. Added a ground and now A/C blows ice cold

 

[Fless]

Was this a ground you repaired? Why was it missing?