^^this
ok well i changed pressure switch and wired everything up and it works. the only thing now is when tank fills i still get a little hum after i blow until air goes down a little…so i should take the screw out valve and then remove chrome cap spray with soapy water, am i correct also loosing air but i know i need soapy water for that.
Well the soapy water will tell you where the leaks are after everything is installed. Put that around the threads of the connections because that is where the air will leak from. If you start seeing bubbles expand, you have a leak and it needs to be tightened, or redone with Teflon tape. Not sure how you would test the valve. Usually, if the tank is empty and you hit the horn button, you should hear a sharp metallic sounding click from the valve when you hit the button. That will tell you if it is working, but I’m not too sure how you would see if air is leaking from it…
You already have your proof. You can hear the air humming through the horn while the valve is supposed to be shut. Don’t know how else to say it - get a new valve.
If you still want to “see” the air coming out of the valve, take it off the horn. Leave the airline hooked up to the input and put your soapy water over the output. Bubblessssss!