It's 'usually' best to check the A/C from the Compressor backwards toward the dash, not the other way around.
I like to start by looking to see IF the compressor clutch is engaged (engine running, AC on). IF it isn't then I will run 12volts directly to the compressor clutch to determine whether or not it is capable of operating. IF it doesn't engage (engine off, 12volts directly to clutch) then it is likely your problem.
IF it does engage then the next thing you'll want to do is check the 'static' pressure of the system (refrigerant charge). You will need a set of manifold gauges to do that. Your system has a binary switch (high/low pressure switch) that will not allow the compressor to engage if the pressure is either too high or low. By checking the 'static pressure' (engine off, AC off) you can see if there is enough system pressure (roughly 35-50 psi) to let the unit operate.
IF there is enough pressure then you'll want to move to the pressure switch itself and test it (check connections and bypass if necessary). IF the pressure switch proves to be good THEN start looking at electrical components (fuses, relays, wiring, switches, etc).
Good luck Sir. A/C issues are always fun.