Cadillac: codes and how to read and diagnose, gm code, number combinations

Question
I have a 86 eldorado with the 4.1 v8 and after I start it it sais system problem on the display along with windsheild washer and another I cant remember. I looked allover for the aldl port and I cant find it. I know alot about gm tpi but im stumped on cadillac motors. how do I go into diagnostics and how will it read out the codes? is it the same as other gm? code 13-14-15 etc? and can you tell me what each one means?

another question. when I start the car the compressor is always running but to my understanding its only supost to run for up to 3 minutes after ignition on? is there a leak?

thank you.

Answer
Get the codes:

1. Ignition ON. Engine OFF.

2. Simultaneously push and hold the OFF and WARMER buttons for 3 seconds on the climate control panel and then release them. Codes should appaer in the form of LETTER/NUMBER combinations and then stop at .7.0.

3.Ignition OFF.

Tell me EXACTLY as if you were video-taping the screen, What you see.