if i buy a kit without a presure switch like this one http://www.hornblasters.com/products/details.php?i=viair-110-150-psi-pressure-switch-with-relay
how will the compressor know when to kick on and give me air? will i have to turn in on myself? or does the compressor know when? please help
Thanks guys
mmm… but why don’t you want a presure switch?? all the hornblaster kits come with a presure switch like the one you post or like this one http://www.hornblasters.com/products/details.php?i=viair-110-145-pressure-switch … but if you don’t want one you will have to get a gauge to know when the tank reach the presure you want and then turn the compressor OFF and ON you know… a compressor without a presure switch won’t know when to stop or when to star…
ok i will prob just buy a good shocker kit! thanks for the info helped alot!
np bro anytime 
The link that you posted… That IS a pressure switch and relay built in one unit… Thats the ideal way to go since its also weather resistant / proof
Dont just put a toggle on compressor, that will void the warranty of the compressor and is simply not worth it for the cost of the pressure switch.
Besides who wants to be driving along starring at the gauge waiting for it to hit the correct pressure and then have to turn it off at exact pressure? 
yes but whats the point in the relay? whats it do?
The pressure switch tells the compressor when yo turn on and most important when to turn off…
So if your pressure switch is set at turning on at 110 psi, and off at 150 psi, the compressor will do just that…
The relay is a fuse basically… It mainly allows the compressor to turn on when the ignition is on… otherwise if you have a leak when you are not in the vehicle , and the pressure drops below your pressure switch setting, the compressor could click on and drain the battery and possible risk damaging the compressor!
That grey box type is the best one to get , it is fairly waterproof, has all marked leads too which is easy for hookup… good luck, any more questions feel free to ask
It can be called a solenoid to.
It’s there to apply and remove power to the compressor. Without it your “on / off” switch and pressure switch would have to handle a lot of current.