I have a 1991 GMC Sierra X-Cab 5.7, manual trans. Everything was great until two days ago. I turned the ignition off and the a/c fan stayed on. I later discovered that the a/c clutch was still engaged as well (killed the battery). I figured it was a stuck relay. I systematically unplugged all three relays on the heater housing, unplugged the a/c control module, and even pulled the fuse for the a/c heater, and with the ignition off, the clutch was still engaged. Disconnect the battery or the pressure switch and the clutch shuts off. There has to be another relay somewhere that is stuck or a direct short, but if it were a short, it would blow something. Any ideas? Thanks, Joe