So button marked "AC" on the tmp control panel is in off but AC pulley still engaged. Hmmm. There's a 2 wire connector on the clutch. Pull that off and it disengages. Test that for a short. Otherwise its the clutch itself.
On call for AC the compressor clutch engages the pulley yes. On NA trucks the AC button turns it on. On JDM trucks the temperature control module does it. AFAIK...