Wondering is there is a test procedure to determine why the A/C clutch will not engage.

2002 Silverado 3500 LT

Symptoms: No cold air, A/C light on dash will light, fan door appears to work from dash to foot to mix to defrost positions.

Known: Freon charge is good, fuses (inside drivers compartment and under hood) verified good. Swapped out relay with another with no effect.

Thanks for any help on this!