air conditioner circuit

I have a 93 sedan deville 4.9 The ac is charged up but comp does not engage . I checked power to the compressor at connector diconnected is 12.3 volts .. If I plug connector into compressor there is no voltage ???? If I apply outside voltage to the compressor it starts.....
Any ideals or wiring diagrams out there .. regards John

The computer has shut off the command to engage the compressor. There is a diagnosic tree to follow that allows you to cancel this error. I'm not familar with the '93 Caddy method, but most GM's require you to press OFF and WARM buttons (simultaniously) on the HVAC controls to get into diagnostics.
The other quick and easy way is to disconnect the battery for 10 seconds and reconnect. This will erase all trouble codes, and your radio stations.

I have done the battery thing and once the compressor worked for 5 minutes then quit again retried the battery disconnect and still nothing ?I will try the diagnostic see if it shows anyhting thx

Then it's low on Freon.

let me know if it sets any "F" codes and I will look them up for you. I have the diagnostic charts for it. Could be low Freon like hyarnell1 said, or just a bad relay or low pressure switch.