With engine off, carefully jump 12 Volts directly to the clutch and see if it clicks. It is a loud click so you won't miss it if the clutch is working.
If it clicks, then you need follow the circuit back from there. You really need a wiring diagram, but you might be able to trace the wires. Make sure you are jumping the correct sensor. On your particular model I don't know which one it is.
If it does not click you have a bad clutch.
If your gauge is accurate, you most likely have enough refrigerant to engage the low pressure switch, but you REALLY need a manifold set to monitor high and low side once you have the clutch kicking in.