Several years ago, I replaced the resistor when my fan stopped working. Problem fixed. A few years later it happened again. This time I replaced the resistor and the fan motor. Problem fixed.
Now it has happened again. I replaced the resistor and fan motor. Now when I reattached the wires, the fan comes on high and will not shut off even when I turn the car off. I replaced the center control panel to no avail.
I would surely appreciate any suggestions.

 

Have you tried pulling the fuse in the engine bay?
When you have the fuse out see if it stays off. Also check for any bare wires or rodent damage.

 

The circuit is simple. There are three pins on the connector to the resistor, and two more wires that go to the blower.

The RED wire on the three pin is battery voltage. The Brown wire is ground. The middle wire is the "control voltage" from the climate module. WIth the car off, is should have zero volts on it, if there is voltage, the speed of the fan is:

1.5 volts - low
7 volts - high

A bad climate module can cause this. Or, a bad (even if it is new) resistor can cause this too.