[Jon Stratis]

Is the LED on the spike changing color? If so, the the problem is between the spike and the compressor.

Look at the DSC - is the LED next to the relay output lighting up when the compressor should turn on? If so, then the problem is between the DSC and the spike.

Is the pressure switch plugged into the correct DIO port? Using the console to output the state of the DIO in that same slot to make sure it's working correctly (carefully and safely pressurize the system using a shop compressor, which has it's own feedback loop to ensure safe operation!).

These are all leading questions to try and figure out where the problem is - there's a long chain of stuff that has to work (pressure switch, wire to the DSC, code, relay output on the DSC, spike, and finally compressor) to get the compressor to turn on/off at the right time. Your best bet is to start at the beginning of the chain and work your way down until you find where it stops working as expected.