2001 Cadillac EL Dorado AC blows hot air before cool

At first, do you mean immediately after start, it has to purge the hot air from the ducts as it's cooling. And when you say nothing at all, is the blower running, and no air is coming out of the dash vents. No codes will display for this system to alert a driver, but there could still be codes in the system. You would need to enter diagnostics, or use a scan tool to retrieve them.