A/C does not turn on

It is hard to say why it won't come on at this point, there are several variables. There is no defect with a switch that I am aware of, have seen some broken wires at a pressure switch once. You could have it scanned for codes and that could narrow it down. If you do this, I am not sure I a generic scan tool can get HVAC codes, so that is a question you will have to ask. If you have onstar, and the account is active, they might be able to run a diagnostic. I don't know if that is just powertrain related, or all codes.

Good morning,

The first thing you need to check is the Freon. If the level or pressures are low, the system will not come on line. You will need pressure gauges for the high and low sides to see the actual pressure.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Beyond that, it could be electrical. I attached a wiring diagram for you to view. Check the fuses for power on both sides.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Roy