sr20det a/c issues

[LordOfTheMiasma]

To make a long story short, a friend had the car years ago with working a/c, i got the car from a dealer auction recently and found the a/c lines disconnected. I hooked them up, and tried to put freon into the low side port.. The car won't take the freon, I am thinking the compressor may be shot and this is why because normally it should kick on and inhale the freon out of the cannister. charging the a/c systems of vehicles is nothing new to me so I am not completely retarded and doing it wrong for those who may wonder . I am not sure where to being tho. I tested the plug that goes into the compressor with the a/c switched on and got .3 volts, There is typically a sensor located elsewhere in the system that tells the compressor to kick on, could that be bad? I have a compressor but don;t want to swap it out without being somewhat sure that is the problem. any help is appreciated