Where are the high-pressure and low-pressure A/C relays located?

That system doesn't have A/C relays, it has a pressure sensor in the high-pressure line that sends data to the ECM and the ECM then controls the clutch relay. If you remove the plug from it, you should find a 5-volt signal on pin 2 (gray wire) a ground on pin 1 (tan) and the last pin is the signal pin from the sensor. It is a variable voltage not a simple on off type switch. What is the issue you are having with the system?