The only way this can happen is if there is a short to power. So, I need you to try three things.
If you look below, I attached the wiring schematic. It shows two fuses and the relay. First, remove the relay and see if the blower motor turns off. If it doesn't, then we are getting power from a different circuit.
If it does turn off, remove one fuse at a time. Fuse 12 is what powers the blower motor when the relay closes, so I suspect it is good. However, check it anyway. Next, fuse 45 (5amp) is what energizes the coil in the relay causing the switch to close and send power to the motor. Remove that and see if that turns it off.
Here is the thing. The HVAC module provides a ground path that completes the circuit. There is an outside chance that has failed.
Try this and let me know what you find. Also, let me know if you are able to change the blower speed and I just want to confirm it has automatic climate control.
See pics below.
Images (Click to enlarge)
Monday, June 13th, 2022 AT 8:05 PM