A/C not cooling

[BigBluediesel08]

Truck was down for 3 months waiting on a trans to get here.. After all was done, fired up the truck and noticed the a/c wasn't cooling. Compressor won't engage at all. Checked fuses and all is good. Passed current to the a/c compressor manually, and it turned on.. There's just no power going to it once I connect it back.. Could it be it needs a bit more freon? And it's not engaging the clutch?

 

[capt dong]

did you check pressures with manifold gauge?