Hitachi Gas Air Compressor just stops running

Oil free compressors are used when oil could contaminate food products, or maybe spraying where oil down the line would ruin a spray job, although adequate filtration to stop the oil getting to point of use

This compressor is small however like other brands in this size range draw 13 - 15 amps. Thats quite a bit of power. The compressor has a thermal breaker that will begin to trip if compressor is hot. I am assuming that the breaker that is tripping is the one on the compessor. I have seen many hitachi breakers fail. Easy to replace with generic 20 amp, cost about $10. Before you replace anything, check amp draw with meter, if within specs try to determine what is causing heat.
example:
cycling too many times per hour (check manual for recommended)
low power due to weak circuit or extension cord
using generator for powering compressor (not recommended)
using low quality oil (use synthetic if hot climate)
air leaking from intank checkvalve back to pump
If no reason to overheat then replace breaker on compressor to 20 amp but watch for overheating. Good luck

There is not really enough information here to properly answer your question. I can make a couple of observations for you though. 1. Compressor, yes this could be the problem, but it is not quite that simple. Is the compressor running when the hot air starts to blow? 2. Capacitor, no I don't believe this is the problem, as if it were a capacitor problem, chances are the unit wouldn't even start. 3. Gas leak, again no, if it were a gas leak, then you wouldn't get an hour of good run time when the unit starts up, repeatedly. Hope this helps.

yes pressure release valve bad!

the air pressure switch is gone, get a professonal 2 fix it just incase anything should go wrong

1.Check the motor first. You can readily see if it's
burned or not. Run a megger test on the motor.
Test run the motor without the compressor.
2. If, it does not run, have it checked at the motor
rewinding shop.
3. Once it is okey, remount the motor, and start it up.

is there oil in crank case buddy

Do you have the facility to top up the oil level on the compressor

If so you may find that the low oil sensor is kicking in and trying to prevent you from running the machine dry.

Cheap oil-less compressor, normal.
If you don't like it, buy one that uses oil and a drive belt.

The burst of air you hear as the compressor shuts off is the cylinder unloading so it will not have to restart against a high pressure load. If the unloader is electrical it would explain the hum that you hear. This could be a normal function.