2000 Cadillac Deville air conditioning

Can you hear the blower motor run? First thing to do is have the error codes read by a shop that can read Body codes for Caddy. If blower runs but no air comes out, the clicking could be an actuator for a door in the a/c plenum. Either a door shaft needs oil, or the actuato needs to be replaced, but a scan will at least give a starting point!

You can pull the codes yourself, off and down on the mode button on the heater controls w/ key in the on position

is the noise down by the gas petel, there is an actuator right there, that 1 is usually the culprit