FAULT CODE P0533

It could be low on refrigerant, or it could be a bad sensor. Back-probe the pressure sensor connector (on the discharge line, near the compressor - it's a 4-way connector) on the dark blue wire with the engine running and the A/C turned to max. If you get no volts, or 5 volts, the sensor is bad. 4.5 volts indicates a properly-operating system, while less than 4.5 indicates low pressure, and anything above indicates high pressure. If low or high pressure is suspected, verify with a set of refrigerant gauges.

If warranted, the sensor can just unscrew. You won't lose refrigerant - there's a valve built in to the line to prevent that. Make sure to use a new O-ring and lube it with the proper oil if you do change the sensor.