we are having a few problems with compressor wiring. With the pressure switch, I noticed that it only has a two pin cord. But the DIO slot has a 3 pin slot. Why is this??? Another thing, every time we hook up the compressor, almost all the motors stop working. I haven’t been able to figure out why.
So the pressure switch needs to be wired to the signal and the negative post on the digital side car DIO port that your using.
As for the compressor could you give us some more information on the wiring and how it’s hooked up that would help
How are you running the compressor if you dont have the switch hooked up, doesn’t the supplied compressor code and sensor default to not run the compressor?
But you may want to have your code shut off the compressor when your motors require more power.
ok. I believe we have figured it out. We have gotten some help. Thanks you for all your help
See this thread here: http://www.chiefdelphi.com/forums/showthread.php?threadid=126500
I just posted some diagrams about the pressure switch and compressor wiring. Hope this helps! 
Thanks, and do you kn ow whats really funny? jalmos is another team member of our team 
thanks for the help!
Oh ok. Haha. I saw 2 threads relating to a compressor issue and I figured I would share the diagrams with you, just in case.
I am still having issues. I plugged in the compressor to relay 1, but it wouldnt work. It worked when we plugged it into DI/O 1. It didn’t run right though. I am not sure why it still wont work
Can you put up a picture of your wiring so we can take a look?
I’m not a programmer by any means but when you enable the robot does the green led next to the relay slots come on? Secondly is the pressure switch wired between the negative(-) pin and the signal (SIG) pin on the DIO? And is the Spike plugged in to the correct relay slot?
https://docs.google.com/file/d/0B3nKLLJ5LSEUNEE3LXlpUDUyOTA/edit
here is a graph of how it is set up