Well, if pressure sensor is bad then compressor does not engage at all. That was an issue with my A/C system and I proved it via INPA (see screenshots above). My second problem was high and low pressures did not equalize quickly enough when compressor is off. That is why I decided to take whole system apart and replace expansion valve, condenser, dryer and flush all the hoses (so, I'll check the hoses during flushing).
If compressor kicks then most likely the pressure sensor is fine. You need to hook A/C gauges to check high and low pressures during the compressor cycles. It might be just low refrigerant issue, or it might be a clog somewhere.