Okay I have a 2000 grand prix GT and the a/c plu isn't getting power I tested ot with the stick light and I can jump the compressor strait to the battery and it comes on. All relays and fuses are good. Any ideas before check the wiring.

Check pressures in the system...if the low side is too low or the high side too high, the compressor won't engage. Beyond that, check the low pressure switch. If you can jumper across it and the system kicks on, you need a new one. Thats a decent start to tracking it down.

Okay I put 3 cans of freon in it and Gauge says full. Dumb question- if I run strait power to the presure switch and have the blower on would it cause the a/c to have power?

you don't have to run power to the low side pressure switch. if your low side pressure switch connector is only two wires, start the car and have the connector off of the pressure switch. take you a jumper wire and go from one wire/pin to the other wire/pin.

if the a/c compressor kicks in, then your low side pressure switch is bad. if it doesn't come on, then you could have a bad clutch, maybe a bad compressor or something else.

what kind of a/c controls do you have? sometimes the digital climate controls can cause issues and the other one can too!

just make sure that your freon is not overfilled. here is a good chart with low/high pressures and outside temps. http://ww2.justanswer.com/uploads/sgm11155/2011-07-17_220252_7-17-2011_2-59-46_pm.png

This maybe too late, not sure if you got your AC fixed or not, but yes, it sounds like a electrical issue. I would start check your power and ground sources such as at your relays, fuses, pressure switches, and controller.
Is your test light safe for computer systems? Many are not and you can damage your pcm with it.
Also, you mentioned that you put 3 cans of Freon in it. Was the system completely empty? If not, you hay have overcharged the system, and if it was empty, you would want to evacuate all of the air and moisture out of the system first before adding 134a to it. Also were they 12 oz cans or 16 oz cans? I think the spec on my 2002 is 2.2lbs. I would assume yours is probably that too, but check the sticker. 3 12 oz cans will but you right in the money on your charge. But you want to warm them up when you think they are empty with warm water to get it all out into the system. 3 16 oz cans would be too much.

Having similar problem along with the #5 position fan long time know about ignition switch.Part time air conditioning caused in my '98GTP by slamming door,hitting a bump,turning you name it. Most likely a bad ground or two under and forward. Bought this new for my wife and she loved it until the 20,000 mile dealership visit when the battery made contact with the radiator and fried the positive side bundle, transmission coolant line,radiator, battery etc. etc. I wanted it gone but she didn't so now with almost 100K I have assumed the pilot's seat along with the head mechanic's plot. Have had two water pumps, intake manifold, all brake fluid and gas lines replaced, front cv joints and axels, the coolant is brown again along with the trans fluid oh! I forgot to mention the first full detail had to be post poned till the dealership added more black paint to the right quarter pannel. ALL in all it is still a trip when you kick the floor like my very long'63 GP back in the south of Cal. Life goes on. blakprix

One thing I observed is that modern cars are having a lot of new features and it's also a problem too. Once any problem We get then we cant resolve it easily. I always prefer heating and cooling near me so that I could adjust as per the environment.