A/C Just quit working

Well my A/C was working, I parked the car and when I got back in it about 30 mins later, the A/C wouldn't turn on, just blew normal air through the vents. So here is where I am at, and hopefully someone can help point me in the direction to go.

I have changed the low pressure cycle switch. When I jump the low pressure cycle switch, the engine revs higher, but the a/c clutch does not engage. When I remove the jumper the engine rev lowers. I have also checked the fuses inside the car by the driver door and the fuse box under the hood. The fuses are good. The system is also charged properly, as verified by a set of a/c gauges.

Any help you can provide is GREATLY appreciated.

Thanks!

AC just quit update

Ok, so I did some more testing. I used a meter and checked the connector going to the compressor. I am getting 13 volts to the connector when the a/c is turned on. However, when I plug the connector in, the clutch does not engage. So I jumped the compressor to the battery.... the clutch engages and the car blows cold air. So, I have 13 volts at the connector, no clutch engagement and if I provide power from the battery then the clutch engages. If I run leads from the connector to the compressor, it wont engage. So now I am lost. Oh, when I run the leads from the connector to the compressor, it seems to be pulling .5 amps, when I run the leads from the compressor to the battery, it seems to be pulling 4 amps.

I appreciate any help you guys can offer!

Thanks.