I have a 2007 Pacifica with ATC. The front blower motor stopped running over the winter. I replaced the blower motor control module and that fixed the problem for about a week. Then the blower went to high speed and only shuts off when the car is shut off. I tried another module and got the same thing immediately at install. Both parts are aftermarket from chain auto parts stores. I can shut off the unit itself with no change to the fan speed. I am able to operate the rear system fine from the control unit. The blend door operates as it should. The heat and A/C all work fine. The only problem is the blower stuck on high. I have 12V on the harness coming into the module and have continuity from the ground wire to metal. I have swapped relays in the fuse block and can feel the relays open and close when the ignition is turned on. So my diagnoses goes a little further now than some of the others I've read.

I know there have been a few posts regarding the front blower running on high with the system off. I've read them all multiple times in trying to fix this problem. I have replaced the blower motor module twice on this vehicle and moved on to trying to see if the control unit itself might be bad. I was told that if I removed the unit and the blower stopped, the control unit was bad. I didn't see anywhere what the problem might be if I removed the control unit and the fan continued to operate. I have the unit completely disconnected and sitting on the passenger seat and STILL the blower runs. Any ideas? Could it be yet another bad module?

Thanks for any help.