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!