Don't go jerry riggin your truck. First you need to know if you have voltage at the compressor when it's supposed to be on. An easy way to tell this is by turning it on and tapping the clutch with a screwdriver or small hammer. If it is just weak it will engage. If you do have voltage then you most likely have a worn or weak clutch. When I was a mechanic we rarely did shims because by that time it's most likely going to need a compressor soon and then you have a pissed off customer returning their car cause you didn't fix it right. I don't know if I would even shim my own compressor. I would rather just replace the compressor and not have to worry about it for another several years.