air ride compressor not coming on

is there a pressure switch in the compressor cause i have power to ride height sensors to the rear silonoid to rear and have power to my compressor but wont come on.i had to run a hot wire to the rear silonoid under drivers door on frame and a hot wire to the compressor to get rear end pupmed back up then i turned the switch off and it has been holding all day but still havent figured out what the heck is my problem...thanks for your time...joe

No pressure switch. What year is it as it may have a relay on the rad, support behind the pass side headlight.

hi it is a 99 eddie bauer exp.there is a 4 wire plug going to compressor and if i use volt meter and use -(neg) on one of the post and touch the other 3 with +(pos) they have power and even the box behind headlight has power to it...