You don't normally run your compressor above 100psi. This is adjustable at the switch. If I remember correctly, one screw is for the low pressure setting (turn on) and the other is your max setting (shut down). Your compressor high setting should shut the compressor down at around 100 psi and kick in where you want it, typically at around 80 to 90 psi.
What is bleeding down is the safety bypass or over-pressure relief valve designed to do what it is doing, prevent the tank from overpressurizing and blowing up.
You also have a pressure regulator which restricts outpressure from the nozzle.
