Ok, like I said in my dash light post - I'm having a couple of issues

Earlier this summer, I noticed that my A/C in my 2001 Impala (base w/dual zone climate ocntrol) wasn't working normally. Last year, I had cold air almost immediately after startup. This year, it took 2 or 3 minutes of driving (long enough for the engine temp to start coming up) before I got any cool air. Now, it doesn't blow cold at all. The light comes on when I press the a/c button, but I can't hear the compressor clutch engage or feel the compressor relay switch. I want to try and fix it myself if possible, so I'm hoping to get some troubleshooting tips...and if anyone has wiring diagrams, that would be great.

This is what I'm thinking may be some options:
1. Refrigerant has leaked from the system and now the low pressure sensor is not allowing the compressor to kick in.
2. Compressor relay has failed.
3. A/C switch or control module (?) has failed...

Please keep in mind that I have no schematics for the system, so I'm only guessing how it works. Please help, it's too hot for this!

 

Take to a shop to get looked at