Cadillac Repair: ac needs service, pcm 5, cadillac deville

Question
i just bought a 1992 cadillac deville .4.9 engine with 32k miles original. the dash says service ac  the air blows warm ,you press auto and it imediately switches toecon . i hooked my freon lines to low side  and jumped the sensor on the drier but the comp will not turn on. the car has a new battery . does the ac controller just have to be reset? also i read on several of your online q&asto check fault codes on dash. i dont know how. i am a 31year dodge mechanic. thank you , sincerely  tom

Answer
1. turn ignition ON. Engine OFF.

2. Simultaneously push and hold the OFF and WARMER buttons on the climate control panel for 3 seconds and release them.

3. Diagnostic codes will appaer on the fuel data screen and then will stop.

4. Tell me EXACTLY what letter/numbers that display as if you were video taping the screen. The screen will stop at PCM?

5. Turn off ignition.