a/c electrical problems

though i'm not a huge user of the a/c myself i do use it from time to time when others are in the car but right now i am having an issue, when i turn the ac on the compressor will hit for a second and then stop, if i pop the relay box and pull the relay just as i'm putting the relay back in i can feel it hit and the compressor will come on, i can wiggle the relay and make it hit on and off in the position and the compressor will follow suit... but when the relay is insterted fully the compressor doesn't work at all... i'm no wiring genius so i haven't the faintest clue where to start with it, any help would be appreciated

are u sure you have refrigerant low refrig will make the comp. cycle on and off