A/C Always On Or Compressor Runs Continuously

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Mazda Tribute, 2003 Mazda Protege5, 2003 Mazda Protege, 2003 Mazda MX-5 Miata, and 2003 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

Stuck engagement.
A/C pressure switch stuck closed.
A/C relay is stuck closed.
Short to ground between A/C switch and PCM.
Short to ground between A/C relay and PCM.
A/C relay to magnetic clutch circuit short to battery power.