Air Conditioning Compressor clutch not engaging...

[81GMCSierra1500]

So, I just went and bought a recharge/retrofit kit for my A/C, and it now has a full charge and no leaks, but I have discovered that my A/C compressor clutch isn't engaging when the lever is turned to "max" or any other settings, what are the potential causes? It was working maybe 3 months ago, but I am suspicious about a possible blown fuse? There are no fuse block diagrams that look like mine, and half the lettering on it is either work off or unreadable/not understandable... Hopefully I can find an answer... next after this, heater!