Ive got a 2005 DeVille that was working perfectly the other day. Yesterday I got home, turned the car off, removed the key and opened the door and realized the blower motor was still running and wouldn't turn off. After playing with the A/C and Heater controls I just got frustrated and pulled the fuse under the rear seat until I had time to ask forum members what they think. I did a bit of googling and read where a lot of people say the Blower Control Module is the problem. I looked up where it's located and this morning I crawled under the glovebox to take a look see. Unfortunately my blower motor looks nothing like the pictures I saw when doing research. According to research the Blower Control Module was between the firewall and the blower itself. All I see on mine is the blower motor but no module. Are there more than one type of configurations on these cars? Is the module the actual issue here? Is my module built into the blower itself?

Attached below is a picture of the blower motor I took this morning.
ANY help would be appreciated, I'm starting to get frustrated and I tend to break things when I get frustrated. 2005 Deville Blower Motor

 

I don't know if your model has a separate or integrated controller/module but IMHO the fact that the blower keeps running after shutting down the car suggests two things; (1) You have full-time power to the fan, and/or (2) there may be a short in a ground wire that allows the fan to continue to run i.e. the control is not breaking connection(s) on shut down.

 

So here's an update. I tested all the HVAC relays with a multimeter and they are all ok (none stuck closed) I also replaced the Blower Control Module the other day. Unfortunately that didn't fix the issue. There can only be two other parts causing this issue, 1. The blower control unit or 2. the Blower Motor is shorted. I'm going to replace the control unit soon and will give an update when I do. I'm hoping it is the control unit because the motor is a PITA to get out and I REALLY hope it's not a wiring issue because that'll take forever to track down. I don't think it is a wire issue since it was working fine for 2 months before it started giving me issues but we'll soon find out.