02 gp gt 3.8l.
Bought the car in 2015 and the ac never worked. The vents just blow hot air and the compressor clutch never engages. Upon pushing down on the shrader valve there is no hissing or indication of refrigerant in the system. Every once in a while the compressor pulley makes a scraping noise typical of these gm compressors because of the springs. I did apply 12 volts straight to the ac compressor and it kicks on with no odd noises while spinning.
Auto zone here loans vacuum pumps and ac gauges. Should I first try vacuuming the system and see if it holds? What about uv dye and those harbor freight battery powered ac 'sniffers'?