[Al Skierkiewicz]

Mohamed,
There could be one or two things that are having an issue here. There is a thermal breaker inside the compressor that takes several minutes to reset once it trips. If you block the air slots on the side and end of the compressor, it will over heat. We are also unsure if the PCM can handle high current for this compressor. I would suggest you connect the compressor directly to the PDP through a 20 amp breaker please. See if it runs for a longer period than when controlled. It should reach well above 120 psi. That compressor is rated for 100psi but can easily pump up to 150 psi if it runs continuous.
The Nason pressure switch is not adjustable. The adjustment that people talk about simply sets the trigger for the internal microswitch. If mis-adjusted it will either not start or not shutoff. The factory makes the correct adjustment during production and then seals the adjustment screw.
It is also possible that you have an electrical issue between the PDP, the PCM (if you are using one) and the compressor. If one of the connections is loose, it will eventually heat up and fail intermittently.